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Acceptance for mailing at special rate of postage | “a ovided for in section 1103, act of October 3, 1917, authorized July 10, 1918. ‘ ae 4 ; tblished monthly by The University of the State of New York ALBANY, N. Y. SEPTEMBER-OCTOBER I919 University of ie State of Ne ew York © New York State Museum Joun M. Crarxe, Director \ CHARLES P. BERKEY AND MARION RICE PAGE PAGE ee ee ne Suc we eeicleie se Sich DENICLUTAL SCOlOPY:.. avnewe seus sme 5 OD actory description......... 7 | Economic and engineering geology 82 ecolosy..x.:..'. ae eee kG sa oeaaa bakin ee 105 taphic oe for- EPSOEaye Deen ccs lA See NN a ements AG) 1 GER Vai 5 hoes kk how ee eae eee Le qs aE. (, ot ear oe G Nov 26 1935 He) ae i 0 tt EO sa 4 ALBANY f _ THE UNIVERSITY OF THE STATE OF NEW YORK 1921 a THE UNIVERSITY OF THE STATE OF NEW YORK Regents of the University With years when terms expire (Revised to November 15, 1921) 1926 Prny 2) SEXTON LL-By LL.D Chancellor ‘Emeritus. - - - — — - - +. 1922 CHESTER S. Lorp M.A., LL.D., Ciao 1924 ADELBERT Moot LL. Vice Chataelion - 1927 ALBERT VANDER VEER M.D., M.A., Ph.D., LL. 1925 CHARLES B. ALEXANDER M.A., LL.B., LL.D. Litt.D.- - - - - - -'=- = = = 1928 WALTER Guest KEtitoce B.A., LL.D. - - 1932 JAMES Byrne B.A., LL.B., LL.D. —- 1929 HERBERT L. BRIDGMAN M.A., LL.D. t93r THomMas J. Mancan M.A. - - - - - 1933 WILLIAM J. WALLIN M.A, - — = = *= 1923 WitiiaAm Bonpy M.A., LL.B., Ph.D. ProsO.WILTIAMT, PB AKER: ec Matt slOe ee Palmyra Brooklyn Buffalo om Albany Tuxedo. Ogdensburg New York Brooklyn Binghamton Yonkers New York Syracuse President of the University and Commissioner of Education Frank P. Graves. Ph.D., Litt.D., U.4.D., LL. Dp: Deputy Commissioner and Counsel Frank B. Griipert B.A., LL.D. Assistant Commissioner and Director of Professional Education _. Avucustus S$. Downine M.A., Pd.D., LL.D., L.H.D. Assistant Commissioner for Secondary Education CHARLES F. WHEELOCK B.S., Pd.D., LL.D. Assistant Commissioner for Elementary Education Georce M. Witty M.A., Pd.D., LL.D Director of State Library James I. Wyver M.L.S., Pd.D. . Director of Science and State Museum Joun M. CrarKe D.Sc., LL.D. Chiefs and Directors of Divisions Administration, Hiram C. Case Archives and History, James SuLitivan M.A., Ph.D. Attendance, JAMES D. SULLIVAN Examinations and Inspections, AVERY W. SKINNER B.A. Law, FRANK B. GILBERT B.A., LL.D., Counsel Library Extension, Witt1am R. Watson B.S. Library School, Epna M. SANDERSON B.A.,; B.L.S. School Buildings and Grounds, Frank H. Woop M.A. School Libraries, SHERMAN WILLIAMS Pd.D. Visual Instruction, ALFRED W. ABRAMS Ph.B. Vocational and Extension Education, LEwis A. WILSON ~ The University of the State of New York Department of Science, December 30, 1920 Dr John H. Finley President of the Universsty Sir:—I communicate herewith for publication as a bulletin of the State Museum, a report on the Geology of the West Posnt Quadrangle. : Very respectfully Joun M. CLarKE Director Approved for publication President of the University Mi es —— shaven ge fountains Newburgh Peecastin ; ili vs N ; cI ai Cornwall-on-the-Hudson reakneck Mountain West Point Military Academy Crows Nest Storm King Mountain rw 3 k Garrison-on-the-Hudson : WEST POINT-COLD SPRING PANORAMA Constitution Island Looking northwest through the northern gateway of the Highlands Cold Spring } ’ j i New York State Museum Bulletin Entered as second-class matter November 27, 1915 at the Post Office at Albany, N. Y., under the act of August 24, 1912. Acceptance for mailing at special rate of postage provided for in section 1103, act of October 3, 1917, authorized July 19, 1918. Published monthly by The University of the State of New York Nos. 225, 226 ALBANY, N. Y. SEPTEMBER—OCTOBER I9IQ The University of the State of New York New York State Museum John M. Clarke, Director GEOLOGY OF THE WEST POINT QUADRANGLE, N.Y. By CHARLES P. BERKEY AND MARION RICE PREFACE The West Point quadrangle is the only one in southeastern New York whose geology can not be appreciated at all without some knowledge of the most obscure phases of metamorphism, mag- matic differentiation and the processes by which rocks may come to represent mixed types. Some of these fields are not well under- stood even by the most experienced workers and others furnish ground for much difference of opinion and interpretation. Many of the problems of origin, history and correlation are surrounded by obscurity and exceptional difficulty. Some of these are matters that workers in the average region do not encounter at all. On this account the West Point report deals at much greater length than would otherwise be advisable with debatable and theoreti- cal questions, such as the discussion of processes of origin, the methods of rock modification, the mechanics of structural con- fusion, and comparison of alternative hypotheses. Metamorphic rocks, so extremely modified by a succession of different influences that one can not now determine what they were or how they are related, are common in this area, and igneous rocks so variable in character, so complex in internal structure and so confused in all their relations that one can not now determine how many separate units to recognize or what limits to give them, are equally charactertistic. vt } ‘i i ’ : n New York State Museum Bulletin Entered as second-class matter November 27, 1915 at the Post Office at Albany, N. Y., under the act of August 24, 1912. Acceptance for mailing at special rate of postage provided for in section 1103, act of October 3, 1917, authorized July 19, 1918. Published monthly by The University of the State of New York Nos. 225, 226 ALBANY, N. Y. SEPTEMBER—OCTOBER IQIQ The University of the State of New York New York State Museum John M. Clarke, Director GEOLOGY OF THE WEST POINT QUADRANGLE, N.Y. By CHARLES P. BERKEY AND MARION RICE PR Pe NOs, The West Point quadrangle is the only one in southeastern New York whose geology can not be appreciated at all without some knowledge of the most obscure phases of metamorphism, mag- matic differentiation and the processes by which rocks may come to represent mixed types. Some of these fields are not well under- stood even by the most experienced workers and others furnish ground for much difference of opinion and interpretation. Many of the problems of origin, history and correlation are surrounded by obscurity and exceptional difficulty. Some of these are matters that workers in the average region do not encounter at all. On this account the West Point report deals at much greater length than would otherwise be advisable with debatable and theoreti- cal questions, such as the discussion of processes of origin, the methods of rock modification, the mechanics of structural con- fusion, and comparison of alternative hypotheses. Metamorphic rocks, so extremely modified by a succession of different influences that one can not now determine what they were or how they are related, are common in this area, and igneous rocks so variable in character, so complex in internal structure and so confused in all their relations that one can not now determine how many separate units to recognize or what limits to give them, are equally charactertistic. 6 NEW YORK STATE MUSEUM Probably few districts can be found anywhere better illustrating the problem of petrogenesis of the mixed gneisses, and this one can not be described at all without undertaking such discussion. We have, therefore, accepted the situation as it is and have devoted our best effort largely to an exposition of the origin and character and relation of such rocks belonging to the West Point district,— the now complex ancient sediments, the almost equally complex igneous members which are everywhere intimately related to them, and those still more complex and obscure rocks whose features in part resemble both the sediments and the igneous types and which are confidently believed to be actual mixtures. The bulletin there- fore is only in part a description of the West Point quadrangle. To almost an equal degree it is a discussion of the principles involved in the origin of our oldest and most complex rocks. Work was originally begun by the senior author of this paper on the Tarrytown quadrangle and a manuscript map has been in exist- ence for many years. Before that work was finished, however, the investigations for the Catskill aqueduct began and new data of importance accumulated so rapidly that it was thought best to delay at least till full advantage could be secured from that study. Later it became apparent that the West Point area held more critical geological material bearing on the origin and correlation of the crystalline schists and gneisses than does the Tarrytown quadrangle. It was finally decided to accept this situation and issue the West Point bulletin first using it as a key discussion of the major genetic and structural problems of the region of crystalline rocks of south- eastern New York. It is not practicable to indicate individual responsibility for the different parts of this bulletin or for the departures from the usual treatment that it may contain. The bulletin is a consistent attempt of a teacher and investigator of several years’ experience in the district to cooperate with a junior associate whose insight into complex geologic problems and whose enthusiasm for field work has made it possible to finish a study begun long ago. ¥ ; h ’ GEOLOGY OF THE WEST POINT QUADRANGLE, NEW YORK Hf INTRODUCTORY DESCRIPTION Location The West Point quadrangle lies between 73° 45’ and 74° 00’ W. longitude and between 41° 15’ and 41° 30’ N. latitude. It is on the Hudson river in southeastern New York and includes a sec- tion of the “ Highlands,” a mountainous belt of country extending in a southwesterly direction from western New England across southeastern New York, northern New Jersey and into Pennsyl- vania. The Highlands belt is only about 15 miles broad where the Hudson river crosses it so that the West Point quadrangle includes the whole belt and also small triangular patches belonging to the lower country both on the north and the south sides. The total area is about 215 square miles and comprises parts of Westchester, Putnam, Dutchess, Orange and Rockland counties. Geography The Hudson river, deep enough for sea-going vessels, flows in a restricted gorgelike trench following an irregular course through the area from north to south near the western boundary of this quad- rangle. There are no other navigable streams; only small mountain brooks or creeks enter the Hudson in this portion of its course. The chief town is Peekskill (10,358 inhabitants) which lies on the east bank of the Hudson in the southern part of the quadrangle on the New York Central Railroad, about 40 miles from New York City. The best-known place is West Point, on the west bank of the Hudson, where the United States Military Academy is located. Other towns are Matteawan, Mahopac, Cold Spring, Garrison, Fort Montgomery and Highland Falls. Three railroads run through the quadrangle; the main line of the New York Central, following close along the east bank of the Hud- son; the West Shore, in similar manner along the west bank; and the Putnam division of the New York Central Railroad along the east side of the quadrangle up to Mahopac Mines. The Interstate Park, which covers large areas just to the west, may be reached from Bear Mountain which is on the West Shore Railroad, or by river steamer. Steamboat service is maintained by several lines between New York and Albany during the summer. Day boats and excursions Mf § y stop at Bear Mountain and West Point. There is good ferry service from Garrison to West Point as long as the river is open, and inter- | ! n | | | | 5 | | | Ww | | | / I i pM Aa | | hy Ik | ft ¥ j» ce ie | By | ly | | py | | gz | i 9 ry | Sy aS aN D Plate 2 Location map showing the position and boundaries of the West Point quad- rangle in relation to the chief geographic lines of the region 4 j eg a [es GEOLOGY OF THE WEST POINT QUADRANGLE, NEW YORK 9 mittent service from Peekskill to Bear Mountain and to Jones’ Point. Roads are numerous, except in the northeastern part of the area, and are fairly good. The state road is very good. It follows, for most of the way, the course of the old Albany post road through Montrose, Peekskill, Annsville, Nelson Corners, McKeel Corners through Clove Creek valley northward toward Poughkeepsie. Other equally good roads run from Peekskill to Pleasantside, Yorktown Heights, Mahopac Falls, and Tompkins Corners. The remainder are unimproved dirt roads, but many of them are fairly good. Some of those shown on the map were originally old wood roads and are now impassable for vehicles, and even in some cases are no longer traceable. On the other hand, new roads made since 1891, when the topographic sheet was surveyed, and even the new state roads, which are the best of all, are not shown on the map. The region is a rugged one with much rocky and untillable ground, and, in many parts, very sparsely settled. In spite of its splendid transportation facilities both by rail and water, the West Point quadrangle contains few important industries. Peekskill, as the center of the trade for the best and most populous portion of the area, is a busy small city, and Cold Spring is the outlet of a small fertile valley, but no other place is much more than a station or a small village with very limited support. The proximity to New York City, however, together with the great natural beauty of the scenery, have attracted many people who have made costly improve- ments. The future of the district depends largely on the develop- ment of summer homes and country estates. The inhabitants of the district outside of the special communities represented by West Point and Peekskill are mostly either small farmers, or traders in supplies and necessary commodities, or are residents with business interests quite outside the activities of the district. Few manufacturing establishments are located here, and none is wholly dependent upon the district itself either for supplies or service. Physical Geography The entire quadrangle, except about 3 square miles in the north- west corner and a small tract on the south margin, lies in the High- lands belt. This is a southwesterly continuation of the New England upland developed on the old resistant crystalline rocks which stand up several hundred feet above the softer Cambro-Ordovician sedi- ments to the north. The northern boundary is an abrupt mountain IO NEW YORK STATE MUSEUM wall 1600 feet high, forming, in the vicinity of the Hudson river gateway, Storm King mountain and Breakneck ridge. The southern boundary on the west side of the Hudson river is a similar wall, where the crystallines are faulted against the Paleozoics and Mesozoics. On the east side of the river, however, the Precambrian rocks decline more gently toward the south and continue to the limits of the quadrangle. The West Point quadrangle therefore bridges across the whole Highland belt from north to south, and includes a small amount of the characteristic physiographic and geologic features of the areas bordering the Highlands on both sides. The country changes from low and gently rolling in the southeast quarter to rugged and mountainous in the west and northwest third, where it is characterized by narrow, steep ridges and straight, nar- row valleys with a general northeast to southwest trend. This habit of relief, strikingly exhibited by such mountain ridges as Breakneck mountain or by such valleys as that of Peekskill Hollow creek, is so regular that it suggests at once some funda- mental structural control in the geology. Here and there more independent masses rise as prominent mountains without any marked ridge habit. Such are Dunderberg and Anthony’s Nose, the sentinels of the southern gateway. Storm King and Breakneck at the northern gateway, however, are parts of one strong ridge trenched by the Hudson river so that the two parts now appear as independent mountain ridges. The average surface elevation changes from 200 to 300 feet in the south to 1100 to 1200 feet in the north. The highest individual points are: Dunderberg, 1150 feet; Anthony’s Nose, 900 feet; Crows Nest, 1396 feet; Storm King, 1340 feet; Bull Hill, 1425 feet; South Beacon, 1635 feet. Across this rough, somewhat mountainous country the irregular Hudson river trench or gorge, one-half to one mile wide, extends — from Storm King southward to Dunderberg, its walls rising sharply from the water’s edge. Both north and south of the mountains the Hudson valley widens out to several miles. An interesting feature of the Hudson gorge is the occurrence of small rocky islands, some of which are connected with the mainland by low swampy ground. The origin of the islands, which are rather unusual in a river of the age and character of the Hudson, will be discussed in a later chapter on the physiographic history of the area. The most remarkable erosion feature of the area is the Hudson trench through the Highlands, for the Hudson river shows here the most extraordinary features of its whole course. GEOLOGY OF THE WEST POINT QUADRANGLE, NEW YORK Il The fact that the Hudson is a drowned river affects its present appearance and behavior to a much greater degree than is usually appreciated. Although the Highlands area is 50 miles from the sea, the water level in the river is essentially sea level and is affected by the daily tides and is also contaminated by the mingling of waters from the sea. Superficially the gorge does not appear extraordinary, but the rock floor of the trench is very deep, though heavily filled with drift and silts and the present water level of this drowned river materially reduces the visible depth of the gorge and thus in part destroys its conspicuousness. The exact depth of the gorge is not known at any point, but explorations that have been conducted in connection with the con- struction of the Catskill aqueduct have shown that it is several hundred feet deep and that at the northern gateway between Storm King and Breakneck mountain it extends more than 765 feet below the present water level. Boring operations at that point penetrated to this depth without encountering bedrock, and indicate that the gorge is filled with a great variety of drift materials and water-laid deposits. The fact that other tests of the rock floor showed solid rock at an estimated depth of 950 feet and the fact that the Catskill tunnel was actually constructed in solid rock at a depth of 1100 feet proves that the rock floor river bottom is somewhere between 765 and 950 feet. (For a fuller discussion of this question, see the chapter on Engineering geology under the item Storm King crossing.) No one knows whether or not the gorge is as deep as this throughout the Highlands, but this is probably its deepest and widest point. The gorge at water level is 3000 feet wide on the average. There are three remarkably sharp turns or angles, at West Point, at Anthony’s Nose and at Dunderberg. These changes in course undoubtedly are induced by the structure of the rock to which the river has become somewhat adjusted. But the river does not follow any single structure entirely across the Highlands belt, and thus it appears that these structures are incidental rather than primary con- trols in the original course of the river. Terraces about 150 feet above sea level are very well marked within the Highlands belt at certain places, but it is a very striking _ thing indeed that there is almost no trace of terrace development at Storm King, Crows Nest, Dunderberg, Anthony’s Nose or Bull Hill. In other words, the massive granite belts show absolutely no develop- ment of terraces whereas terraces are prominently developed on the I2 NEW YORK STATE MUSEUM complex gneisses. They are especially well developed along certain stretches on the east side where the land in places runs back almost level for half a mile to the foot of the bordering steep hills. This terrace development has given opportunity for establishment of such settlements as West Point, Cold Spring, Garrison and High- land Falls. It is not continuous enough, however, to be made use of by the transportation lines which on both sides of the river follow close to the water’s edge, and which are constructed by cut- ting and tunnelling and sometimes even by running out on the glacial fill and alluvium of the river. In some places this drift and silt support has been rather unstable and has required considerable protection from stream erosion. If one pictures the rock gorge in its true cross-section without its filling it is very striking that the West Shore and the main line of the New York Central railroads are perched along the sides several hundred feet above the bottom, not even on the terraces, but sometimes following along the rock wall in narrow notches and tunnels and sometimes resting on the - loose drift fill. The tributaries to the Hudson are all very small streams. Those that enter the gorge are unimportant, both in size and number. North of the Highlands, Fishkill creek flows in from the east over the flat lands, and near the south margin, Peekskill Hollow and Annsville creeks empty together into the Hudson. Some of the tributary valleys have the typical U-form character- istic of glacial erosion and some of the smaller ones are hanging. In the back country drainage is comparatively poor because of glacial deposits, and small lakes are common. Some advantage has been taken of these natural basins in the making of larger water storage reservoirs in water supply development. Soil The quadrangle as a whole is rocky and rugged with many bare rock stretches and a very stony, poor looking, or difficult working soil. This is true of great portions of the north and west sides of the area. It is not true, however, of the southeast portion nor of some of the principal creek valleys, such as Foundry brook or Peeks- kill creek, where there are very good farmlands. Occasional upland localities have good soil, but these are comparatively rare. The soils, with few and insignificant exceptions, are of glacial origin and have the variety that characterizes drift soils and drift accumulations. The glacial ice which swept over this region came in GEOLOGY OF THE WEST POINT QUADRANGLE, NEW YORK 13 general from the north, and, in part, across very long distances, carrying with it many kinds of foreign material which mixed with the materials that belong within the district. Since these local materials are derived chiefly from crystalline hard rocks, the most - abundant constituents of the soil especially in its coarser portions are more or less decayed fragments of these rocks. The finer material has come from longer distances in surprisingly large amount and has mingled with coarser matter of local origin. In many places extensive accumulations of fine sands and sandy soils show large ‘amounts of material that could have been derived only from the slates of the Hudson River valley. Occasional boulders of entirely foreign sort must have come from the Catskills, or in more rare cases, even from the Adirondacks. As a result of such an origin the soils are of a strikingly mixed type, bouldery, gravelly, or sandy, with preponderance of crystalline material. In many of the valley bottoms and in small areas where irregular distribution of drift made swamps in former times, heavy silts and muck soils have been developed. But there is no simple law of their distribution; each case is dependent on local conditions, only a part of which is dependent upon the rock floor topography. In some of the valleys the drift is very deep. The tendency of glaciation in this district was to subdue the relief that must have characterized the Preglacial highlands. Pinnacles of rock were undoubtedly worn down and carried away, and the deeper irregulari- ties or depressions were subsequently filled or partially filled with drift. It thus happens that in some places the soil cover is very thick. In the southeast corner of the quadrangle, for example, the drift is so heavy that few outcrops of rock ledge can be seen, and a very critical structural relation belonging to that area is hopelessly obscured by the heavy drift. The district does not show any particularly valuable or excep- tional type of soil and in the nature of the case, no particular quality could be expected to cover a large area. This is a district, therefore, where it is not safe to assume that any piece of land carries good soil simply because it is surrounded by or adjacent to land which is known to be good. There is no residuary soil of economic conse- quence. A few remnants of residuary soil have been observed and one’ of these cases in particular has been the cause of considerable attention in connection with the construction of the Catskill aqueduct. * This is the north end of the Garrison tunnel; for a description of it, see chapter on Engineering geology. I4 NEW YORK STATE MUSEUM Climate The climate of this district is more severe than at New York City. Although only 50 miles inland it is not greatly affected by the influ- ence of the sea. The winters are cold, temperatures of 30 degrees below zero having been recorded, whereas such a temperature has never been known at New York City. A difference of about 20 degrees between these two places is common. It is not, however, quite so cold on the average as the Catskills 50 miles farther to the northwest and not nearly so cold as the Adirondacks 150 miles farther north. In the summer, although the temperature is as high as on the coast, excessively humid atmosphere is seldom felt. Rainfall amounts to approximately 48 inches a year and is heaviest in the spring and early summer. The average yearly rainfall is well enough distributed through the summer so that vegetation is kept green and farms seldom suffer seriously from lack of moisture. Discovery and Colonial History In 1609 Henry Hudson, an explorer of English birth sailing under the Dutch flag, entered the Hudson river and proceeded as far as Albany. The lower Hudson on the present site of New York City was the second permanently occupied spot within the borders of the United States. In 1613 Adrian Block built rude huts in which to spend the winter there. Hendrick Christiansen established a fort _ at Albany in 1614 and inaugurated commerce on the Hudson river, the three-hundredth year of which was celebrated 1914. Settlement pushed up the river slowly because of difficulty and dangers but at least two attempts to establish settlements beyond the Highlands were made before 1655. In that year a strong out- post was permanently established at Kingston. From that time on the territory of the Highlands was more or less fully within the control of the white man, although the natural ruggedness of the country and its resistance to cultivation has kept parts of it even to this day almost as wild as it must have been at the time of its discovery. Revolutionary History The barrier of mountains known as the Hudson Highlands, tra- versed by the narrow gorge of the Hudson river for some 12 miles between Peekskill and Cornwall, separates the Westchester county area from the fertile farmland of Orange and Dutchess counties. This wild and inaccessible belt with its woods and precipitous cliffs GEOLOGY OF THE WEST POINT QUADRANGLE, NEW YORK 15 played an important part in the Revolutionary War and in fact may have determined the political destiny of the American colonies. General Washington, defeated in the battle of Long Island and driven from his strongholds in New York and the lower part of the river, removed his headquarters to Newburgh on the north side of the mountains. For over two years he remained behind the shel- ter of these hills, with just enough strength to man his positions and oppose the British advance, though constantly threatened by a persistent enemy and once almost betrayed by the traitor Burr. In October 1777, while Washington was in the south, the Hudson pathway through the hills was captured and all the fortifications in. the Highlands were destroyed by a British force under Sir Henry Clinton in a brilliantly executed attack. Landing on the east side of the river at Verplanck’s Point, this able commander caused General Putnam, who was holding the Albany post road with his main force encamped at Continentalville, in the valley north of Peekskill, to withdraw most of his forces from the west to the east bank. The British force then quickly crossed to the west side of the river and found its way to the west of Dunderberg by a rapid march through the Timp pass. The objective was the forts guarding the approach to West Point, which were well placed upon the terrace so strongly developed on the west side of the river. Once upon the smooth bench above the river, the British took Fort Montgomery in spite of a stubborn defence by the small force of Continentals, who were aided by the deep and easily defended trench of Popolopen brook, and in a few days the forts were all destroyed, and this topographic stronghold was in British hands. - But defeats in the north forced the abandonment of the areas, and Washington, perceiving the importance of retaining control of this natural fortification, rebuilt his forts and stretched chains across the river to prevent the passage of the hostile fleet. Thereafter, in spite of diminished resources in men and munitions, he successfully retained his positions until the end of the war. This rough wild country was an effective barrier to land com- munication except on the river itself up to the time of railroad building. But the railroad and the river together soon became the best route of emigration to the great unsettled interior regions. Since that time commerce has followed the same line in such volume that New York City, as the principal port to benefit by the advan- tages of this natural route, has become the greatest trade center of the continent. 16 NEW YORK STATE MUSEUM GENERAL GEOLOGY Introductory and Historical The variety of rock types in the Highlands has been recognized since the beginning of the study of geology in America. Amos Eaton in his Index to the Geology of the Northern States says in ‘speaking of this district, “I believe every known variety of granite is found here.” The writers are convinced that this was a fair approximation to the actual facts. The first careful study of the region was made by W. W. Mather in 1843.2. In spite of the short time allowed for the completion of ‘the work, necessitating the covering on an average of 30 square miles a day, not only were the broad general features recognized and described but a remarkable amount of local detail was collected. When the different use of technical terms is allowed for, his state- ment of the causes underlying the complexity of the country is seen to indicate a remarkable insight into the more difficult and obscure phases of Precambrian metamorphic and igneous geology, and is on the whole strikingly similar to the most recent conceptions. He seems to have regarded the region as made up of sedimentary strata metamorphosed by intrusives of great penetrating power. He con- tinually mentions “the granite laminated among the limestone strata” (p. 484), “the granite interstratified with the gneiss” (p. 525), ‘“‘the greenstone which is intruded in sheets and irregu- lar masses among the gneiss and other rocks in the same way as granite and syenite” (p. 532). He noted the association of the hornblende gneisses with the magnetite veins, “the hornblendic rocks are constantly associated with the beds of magnetic oxide of iron which are so numerous in the Highlands” (p. 534), and understood the true igneous character of the veins, ‘‘ They form masses in gneiss and hornblendic gneiss rocks, which by casual examination would be called beds, but after careful examination of the facts I think they may be called veins. They lie parallel to the layers of rock, but by close examina- tion it is found in many instances after continuing this parallelism for a certain distance, the ore crosses a stratum of rock, and then resumes its parallelism, then crosses obliquely another and so on. In other places where a great bed of ore occurs at some depth, only a few small stripes of ore penetrate through the super- incumbent mass to the surface, as if the rocks had been cracked * Mather, W. W. Geology of New York. Part I, comprising the geology of the First Geological District, 1843. GEOLOGY OF THE WEST POINT QUADRANGLE, NEW YORK 17 asunder, and these small seams of ore had been forced up from the main mass below” (p. 559). ‘“‘ The phenomena of the mines in many places on this vein (the Phillips vein) induce the idea of igneous injection, connected with a powerful upheaving force. The feldspar is often pearly, wrinkled, and with bent laminae. The appearance of hyalite, a mineral usually associated with volcanic and trap rocks; the apparent injection in veins among the seams and crevices of the rock; the appearance of softening of the gneiss and bending of its layers like flowing slag, seem to point to an igne- ous origin of this vein” (p. 564). Such statements show an extraordinary grasp of the processes which formed the Highland rocks, and it would be difficult even with the newer phraseology, after nearly 80 years of development of geologic science to describe the salient features better or to paint the minor structural peculiarities as well. Mather’s description of the larger structural features of the Highlands also is worthy of note. “The Highlands in Rockland and Orange are a continuation of those of Putnam and Westchester counties, and are similar in general aspect, in the kinds of rocks, and in their mineral products. The rocks consist of gneiss, and hornblendic gneiss, syenite, granite, limestone, hornblende, serpentine, augite and trappean rocks. The strata dip to the southeast at angles from fifty to ninety degrees, but there are localities where the strike and dip are transverse to the general directions. The strata are intersected by seams trans- verse to the direction of the strata, and nearly perpendicular to the line of bearing, and at intervals of one hundred to ten thousand yards. Dislocations and vertical and lateral heaves have occurred along many of these lines of fracture. The outcropping edges of the strata are not parallel to the line of bearing, but like the ridges, slope gradually down to the northeast; while on the southwest, steep escarpments range along the lines of faults. Many of these faults are upon an enormous scale, and render the tracing of narrow beds of rock of economical value a matter of no small difficulty. There are no continuous ridges of mountains of more than a few-miles in length, in consequence of the interruptions caused by dislocations and lateral heaves of masses of the strata. The hills of similar rocks succeed each other in echelon lines, which seem to shave been caused by lateral heaves along the lines of fault. In consequence of this, neither the line of outcrop nor the line of bearing is parallel to the general direction of the Highlands, but 18 NEW YORK STATE MUSEUM ridge succeeds ridge, each of which runs out and diminishes in height until it disappears below the rocks which are generally con- sidered of more recent origin”’ (p. 517). Since Mather’s time no very large amount of areal work on the Highlands has been published, although various investigators have ' worked in the region in connection with special problems. James D. Dana in 1880 studied the limestones of Westchester county.* He states that the limestones are interbedded with the gneisses and that Westchester county owes many of its topographic features to its limestone belts which determine river valleys, marshes and lakes (p. 28). In the West Point quadrangle he observed that the limestones in the southern part have an east-west trend which is abnormal in this region, and also that the two largest valleys in the Highlands proper, Conopus hollow and Peekskill hollow, are developed on limestone. In 1896 The University of the State of New York published a map of the State which represents the Hihgland region differently from the map published with this bulletin. The chief discrepancy lies in their correlation of all the limestones as upper Silurian. The more recent work in the area indicates the presence of both Precam- brian and Paleozoic limestones. On the adjoining regions of New York, Pennsylvania, Massachu- setts and Connecticut, various papers ° have been published. In the Raritan folio® a more fully matured and complete descrip- tions of the formational units recognized by the New Jersey Survey may be found. The same divisions are supported as in the earlier publication and thus the names Pochuck, Losee and Byram gneiss have become firmly established. The authors of these New Jersey folios divide the Precambrian series into two main types, sedimentary and igneous. The sedi- mentary is now represented only by the limestone strata and by part *Dana, J. D., Limestone Belts of Westchester County, New York Amer. Jour. Sci: and Art. v. 20. 1880. *“ Geological Map of the State of New York. F. J. H. Merrill. U.S. Geol. Survey Geologic Folio No. 161. Franklin Furnace Folio (1908). Spencer, A. C., Kummel, H. B., Wolff, J. E., Salisbury, R. D., Palache, Charles. U. S. Geol. Survey Geologic Folio No. 162, The Philadelphia Folio. Bascom, F., Clark, H. B., Darton, N. H., Kummel, H. B., Salisbury, R. D., Miller, B. L., Knapp, C. N. Geological Map of Connecticut. Conn. Geol. and Nat. Hist. Sur. Bul. 7 (1906). Gregory, H. E., and Robinson, H. H. Geological Map of Massachusetts and Rhode Island, U. S. Geol. Survey Bul. 597 (1916). Emerson, B. K. * Geologic Folio No. 191, U. S. Geol. Survey (1914). The Raritan Quad- rangle. W. S. Bayley, R. D. Salisbury and H. B. Kummel. GEOLOGY OF THE WEST POINT QUADRANGLE, NEW YORK 19 of the Pochuck gneiss. The igneous is represented by three gneisses, the Pochuck, Byram and Losee, which are the dark-colored, medium, and light-colored types respectively. The Pochuck gneiss is horn- blendic and probably corresponds to the hornblendic gneiss of the West Point sheet. It is believed to be partly igneous and partly sedimentary, but so much metamorphosed that the original character is indeterminable. Its relation to the other gneisses is unknown but probably it is older. The metamorphism may ‘have been pro- duced during the invasion of the granitoid gneisses. Those, known as the Losee and Byram, are more distinctly granitic and are inter- layered with the Pochuck and with each other. Granite and peg- matite cut all the gneisses. The following quotations suggest the chief structural concep- tions: “The limestone and dark gneiss together seem to constitute a matrix holding the intrusive granitoid rocks in the form oi rela- tively thin but extended plates.” The gneisses are “so intricately mingled that detailed representation of their distribution is quite impracticable.” “The varieties of gneiss are seldom found in large masses free from intermixture with other sorts, but the different facies or varieties occur in tabular masses which are interlayered both on a large and ona small scale.” ‘“ That large amounts of pre- existing rock material have been more or less completely dissolved or assimilated by the invading magmas is suspected, but can not be ascertained.” “Throughout New Jersey evidence of crushing in the minerals of the gneisses is almost entirely wanting, and appear- ances strongly favor the belief that the gneissic foliation is original in the invading rocks of the Precambrian complex.” On the opposite side of this field in close enough proximity to demand equally careful consideration is the work of the Connecticut _ State Survey. The new state map includes representations of some of the same formations. The Connecticut geologists have rendered a good service in the discrimination of differences and in marking bounds and limits, but liitle attempt is made in the matter of cor- relation or genesis of the more obscure types. In 1905 the senior author of this bulletin began work on the crystallines of southeastern New York for the New York Survey, starting in the Tarrytown quadrangle. The New York City area immediately south had been mapped and the description of its geol- ogy had been issued as a geologic folio’ so that this seemed to be the niost logical place to begin. “Geologic Folio No. 83, U. S. Geol. Survey (1902). New York City and Vicinity. F. J. H. Merrills, N. H. Darton, A. Hollick, R. D. Salisbury, R. E. Dodge, Bailey Willis, H. A. Pressey. 20 NEW YORK STATE MUSEUM Little opportunity to subdivide the basal gneiss member is pre- sented in New York City, but through this piece of work the terms “ Fordham gneiss” and “‘ Yonkers gneiss ’’ were established. Hud- son schist, Stockbridge dolomite and Lowerre quartzite were used for younger members of the crystalline series. The first two terms have been used consistently by all workers since, but, because of the correlation difficulties introduced by those terms, the local terms “Manhattan schist’ and “ Inwood limestone” have generally been favored by students in this district in referring to the younger formations. The authors of folio 83 have correlated the crystal- line limestone-schist series of New York City with the Hudson River- Wappinger series of the Upper Hudson valley. This whole matter of correlation, however, is considered by the present writers a very unsettled problem and a careful summary of the arguments on both sides is given in this bulletin on a later page. (See page 128.) The work begun in 1905 for the New York Survey on the Tarry- town quadrangle was still incomplete when the exploratory investi- gations of the New York City board of water supply were inaugu- rated preliminary to the planning and construction of the Catskill aqueduct. The senior author of this bulletin was appointed geologist for this undertaking, and it thus became his duty to examine critically the whole region between the Catskills and New York City. Unusual opportunities were thus presented and it soon devel- _oped that considerable revision of the geology might be expected. Exploration and construction has taken more than 12 years and, in view of the fact that considerable change of conception concerning the geology of the more ancient portion of the region was develop- ing, it was not thought desirable to issue so permanent a publication as a folio or a quadrangle bulletin until more stable hypotheses as to the nature and origin and grouping of these rocks were evolved. In the meantime, however, several papers® of the nature of pre- * Berkey, Charles P. Structural and Stratigraphic Features of the Basal Gneisses of the Highlands. N. Y. State Mus. Bul. 107, p. 361-78 (1907). Berkey, Charles P. Geology of the New York City (Catskill) ‘Aaiedates N. Y. State Mus. Bul. 146 (1911). Colony, R. J. High-grade Silica Materials for Glass, Refractories, and Abrasives. N. Y. State Mus. Bul. 203-204 (1917). Fenner, Clarence N. The mode of formation of Certain Gneisses in the Highlands of New Jersey. Jour. Geol. 22:594-612. (94-202), (1914). Fettke, Charles R. The Manhattan Schist of Southeastern New York State and Its Associated Igneous Rocks. Annals N. Y. Academy of Sciences, 3 :193-260 (1913). Gordon, C. E. Geology of the Poughkeepsie Quadrangle. N. Y. State Mus. Bul. 148 (1911). Kemp, James F. Buried Channels Beneath the Hudson and Its Tributaries. Am. Jour. of Science. Ser. IV, 26:301-23 (1908). GEOLOGY OF THE WEST POINT QUADRANGLE, NEW YORK 21 liminary statements and discussions of particular formations or special problems have appeared. These were all inspired by and directed along the lines developing with the new studies just described. It is needless to say that such formational studies as those on the Cortlandt series:by Rogers and the Manhattan schist by Fettke are the most detailed ever made on these formations and they are accepted as sound both in observation and interpretation. The remaining important formations deserve similar special treatment. The bulletin on the Geology of the Catskill Aqueduct® contains some of the newer geologic developments from the investigations of the Catskill water supply project; but the purpose of that study did not yield to much elaboration of purely scientific discussion, such as detail of origin and structural habit and age or correlation of geologic formations. As investigation and exploratory development progressed, it came finally to be appreciated that the West Point quadrangle contains the most suggestive and critical ground of the whole region and that it could be made a key study for southeastern New York. On this account the West Point quadrangle was selected as the one to receive earliest publication rather than the Tarrytown quadrangle, - on which work was first begun and whose areal map has been in manuscript form for several years. On the north side of the Highlands the Poughkeepsie speciale includes patches of the Highlands rocks and great areas of the Poughquag-Wappinger-Hudson River series of sediments. This district has been described and mapped by Clarence E. Gordon.” It is in some ways a critical district. Within its borders the Hudson river slates seem to transform gradually into highly metamorphosed schists in passing eastward until they can not be distinguished in appearance from the Manhattan schist of the south side. Mr Gor- Kemp, James F. Geological Problems Presented by the Catskill Aqueduct # sy City of New York. Jour. of ‘Canadian Min. Institute, 14:472-78 IQII Kemp, James F. The Storm King Crossing of the Hudson River by the i , Aqueduct of New York City. Am. Jour. Sci. Ser. IV, 35 :1-11 1913 Ridgway, Robert. The Hudson River Crossing of the Catskill Aqueduct. Jour. of the N. E. Water Works Assn., v. 25, no. 3 (1911). Rogers, G. S. Geology of the Cortlandt Series and Its Emery Deposits. - Annals of the N. Y. Academy of Sci., 21:11 -86 (1911). Stewart, Charles. The Magnetite Belts of Putnam County, N. Y. School of Mines Quar., 29 :283 — o (1908). °N. Y. State Mus. Bul. ” The Geology of the Boneaieeoeie Quadrangle. .C. E. Gordon. N. Y. State Mus. Bul. 22 NEW YORK STATE MUSEUM don’s discussions of correlation problems therefore are of special interest in connection with the West Point studies. On the south side, Charles R. Fettke’* has made a special, very detailed study of the Manhattan schist. His contribution therefore supplements that of Mr Gordon. - The latest contribution” bearing directly on the geology of this district is that by R. J. Colony, which is confined to the Poughquag formation and its petrographic and chemical character. Geologic Formations The quadrangle is composed almost entirely of Precambrian gneisses, schists, and limestones (the Highlands gneiss, Inwood lime- stone, Manhattan schist) and their associated intrusives. In the northwest corner a small area of the Hudson River series (Ordovician) appears and in the southwest is another small area of the Cambro-Ordovician quartzite, limestone and shale. The Manhattan schist is cut by the Peekskill granite and Cortlandt gabbro-diorite series of uncertain age which lie east of Peekskill. The Highlands gneiss, which makes about 70 per cent of the total area, is considered to be the age equivalent of the Grenville gneiss and associated series of the Adirondacks and Canada, but here it is so penetrated and replaced by granites that its original character can be distinguished in few places. The chief belt which approaches the Grenville in character lies along the Hudson river where it - shows as a series of thin calcareous, micaceous and quartzose beds cut by granites and pegmatites, and is much sheared and distorted by faulting. Almost all the remainder of the Highlands area is either granite or gneiss so granitized that it could readily be taken for a granite. The chief proof of the original sedimentary character of the country is found in the interbedded limestones, the largest of which underlies the valley of Sprout brook. There has been extensive granitic intrusion and replacement throughout the area, and so intimate a mixture of granite and gneiss has been formed that it is usually difficult to determine the origin of any given outcrop. The simplest igneous rock of the region is the Storm King granite which forms Breakneck ridge and Bull hill on the east side of the Hudson, and practically all the mountainous area on the west side. The general strike of the gneisses is northeast-southwest and the dip of the principal structure is steep to the southeast. “ The Manhattan Schist of Southeastern New York State and its Associated Igneous Rocks. Annals N. Y. Acad. Sci. 23 :193—260 (1913). “High Grade Silica Materials, N. Y. State Mus. Bul. 203, 204. GEOLOGY OF THE WEST POINT QUADRANGLE, NEW YORK 23 The Inwood limestone and Manhattan schist lie in the southeast part of the quadrangle. The limestone lies almost east-west and dips south. The schist overlies it conformably. The Hudson River shales are faulted against the Storm King eranite on the north. At the south a long fault runs northeast- southwest from Kent cliffs to Tompkins Cove. This is a continua- tion of the fault system which makes the Ramapo mountain escarp- ment to the southwest. An infaulted band of the Cambro- Ordovician sediments about one-half of a mile wide follows along this fault from Adams Corners on Peekskill Hollow creek to Peekskill, continuing across to the west side of the river and through Tompkins Cove southwestward. The Cortlandt intrusives lie at the angle made by two faults or a fault and a strong flexure, the continuation of Peekskill Hollow fault and the Mahopac flexture. They are distinctly unmetamor- phosed and show no signs of a complicated dynamic history. Formations sufficiently prominent to be mapped. Several easily distinguished groups of formations are represented and in each group there are a certain number of readily distinguished members. The principal groups fall into a historical sequence, but there is no intention to discuss that relation at this point further than to present the general sequence from older to younger. The great divisions or groups of formations are: 1 The ancient Precambrian gneisses, schists, granites and a variety of related rocks. 2 The Manhattan-Inwood-Lowerre series of crystalline schists and limestones which is of questionable age. 3 The Hudson River-Wappinger-Poughquag series of slate, lime- stone and quartzite of Cambro-Ordovician age. 4 The Cortlandt series of later intrusives. The relative areas represented by these four groups on the accom- panying geologic map bring out the fact that group 1, the ancient Precambrian gneiss-schist-granite series, occupies about two-thirds of the whole area and is the dominant group of this quadrangle. The second group, crystalline schists and limestones of doubtful age, is found only in the southeast quarter of the quadrangle. The fourth group, the Cortlandt series, occupies a compact area extending into the quadrangle from across the south line and covers about 20 square miles. The third group, the Hudson River-Wappinger-Poughquag series, is found in a triangular patch in the northwest corner of the quad- 24 NEW YORK STATE MUSEUM rangle and in one long downfaulted strip along Peekskill hollow and across the Hudson river to the south margin of the sheet. The amount of territory covered by the three minor groups is not very different one from the other. They are all small and comparatively insignificant in contrast to the dominant series represented by the ancient crystallines of Precambrian age. The drift cover on the north margin and in the southeast quarter of the quadrangle obscures the boundaries of these groups so that mapping can not be done accurately, but over most of the quadrangle the major divisions are easily distinguished and are mapped with fair precision. In most cases, however, where the attempt is made to distinguish the minor subdivisions much greater difficulty is experienced. This difficulty is measurably increased by the fact that some of these smaller members are found only in those areas already referred to as being obscured by drift. The greatest uncer- tainty of this sort is in the southeast quarter, where certain critical structural relations must exist, but can not be seen because of the heavy cover of glacial deposits. On other portions of the area, more elevated and rugged, repre- senting the Highlands belt proper, outcrops are numerous and very extensive, and the difficulties emphasized above do not exist, but other greater ones appear. In this case the difficulty arises from the normal obscurity of the structural relations and the great variability of appearance and quality of the formations them- selves. It is the sort of problem that always confronts one in attempting to draw lines of division in a series which seems to have all sorts of gradations and transitions and no sharp boundaries. The best that can be said in the matter of formational subdivision of this ancient series of gneisses and granites is this: Certain dominant types are recognized as fundamentally distinct and all the variations noted in them and between them are understandable as develop- ments from these fundamental units under the history indicated for the region. (See statement of the petrogenesis of this series, page 29.) There is very great petrographic variability in nearly all forma- tions of the quadrangle. This is particularly true of the more ancient ones and less true of those representing’ slightly metamor- phosed sediments. But all that have Precambrian history exhibit elaborate petrographic variations, some of which are extremely diffi- cult to interpret. It is this great variability of the members them- selves that has always made it difficult to do geological work in the GEOLOGY OF THE WEST POINT QUADRANGLE, NEW YORK 25 Highlands and that has appeared so hopelessly confused to the average observer. For example, it is no unusual thing to pass, within a short distance, from simple typical granite to typical banded gneisses and perfectly typical schists, and even to carbonate and lime silicate streaks representing former limy beds, without being able to draw a sharp line anywhere between the different portions. Such changes take place not occasionally, but repeatedly in a most con- fusing series of repetitions and variations. Then again a formation that seems to be a simple granite will in a short distance, without _ any apparent line of demarkation, pass into a rock of streaked struc- ture which would, if seen alone, certainly be called a gneiss. If specimens were taken from two such nearby outcrops, it would scarcely be considered conceivable that the two could belong to the same formation and yet frequently in the field, where every inch of ground is exposed, there is no possible line of separation between them. It thus happens that one becomes accustomed to including great ranges of quality and structural habit and mineral make-up within the bounds of a single field unit. If one were to attempt mapping on any other basis than this in the Highlands of New York, it could not be done on any scale much smaller than the ground itself, because some of these variations take place within distances of ‘inches instead of feet or rods. And in those formations which have the most complicated history, differences in quality occur by the thousands in every conceivable method of arrangement, distribution and repetition. It is necessary, therefore, to develop some method of generaliza- tion as the only practical measure, and the best basis for this is _ judged to be the origin and history. Units which have a definite Origin or an understandable sequence of development of variations both within their own boundaries and upon their neighbors are considered objects of special significance. All petrographic varia- tions are referred to one or another of these units. It is readily appreciated that generalization of this sort) leaves much to be desired in the detail mapping and it is not assumed that mistakes have been wholly avoided; but it is the belief of the authors of this bulletin that a large part of the complexities of the geology of the Highlands may be made quite understandable on this basis. It gives a better interpretation of the area than could be derived from the most elaborate undertaking that tended to emphasize individual differences rather than the larger and more fundamental similarities. 26 ve NEW YORK STATE MUSEUM Almost every variety of igneous or metamorphic rock that could be obtained by the differentiation of granite magmas and their attack on country rock is to be found here. And there have been several magmatic invasions, each making its own particular addition to the existing confusion. The more ancient gneisses, schists and limestones, already complex and obscure, are made even more so by contact influence and by magmatic and mineralizer impregnation of most elaborate character. This latter has served to mix, in hope- less confusion, constituents of original sedimentary with con- stituents of later igneous origin into a rock that is neither the one nor the other, but which can be understood as essentially an impreg- nation gneiss. There are also the banded types which are, in part at least, lit-par-lit injection of simple igneous matters along the weaknesses of the invaded rocks, all of which had been previously metamorphosed and may already have been impregnated. Suc- cessive attacks of this sort are not rare and a particular outcrop may contain representatives of practically all the igneous members of the Precambrian series. Under these circumstances, quartzites may not be distinguishable from gneisses nor determinable as to igneous or sedimentary origin ; and schists may be made from either recrystallized sediments or sheared igneous rocks. Limestones may be so changed by subtrac- tions, additions and reorganizations of their constituent minerals as to be scarcely distinguishable as limestones at all. It would be a mistake to assume that all the formations are so confused or that they all show such indeterminate penetrations and gradations. It is somewhat less characteristic of the Storm King granite than of the other Precambrian granites, but even this is, in some places, quite confused. The Grenville also, especially those beds in which limestones are prominent, seems to be readily distin- guished. But one needs little experience to become convinced that even this simplicity is more apparent than real, for it is frequently impossible ‘to or 15 feet away to determine whether one is dealing with an old sediment or an igneous rock. As far as appearances and structure are concerned, it might be either. The chief types of rocks. It thus happens that one may list an exceedingly large number of rock species from these members of the Highlands series — enough to stock a museum of acid igneous rocks of intrusive and plutonic types, and the whole gamut of metamorphic rocks. The most abundant types, however, are the following: GEOLOGY OF THE WEST POINT QUADRANGLE, NEW YORK 27 Granites of many varieties, chiefly biotite or hornblende or pyroxene granite, and soda granites. Pegmatite of great variety representing every extreme from pure quartz pegmatite on one side to magnetite ore on the other. _ Dioritic rocks, both massive and gneissoid. Basic igneous rocks (not very abundant in the Precambrian). Dunite and gabbro and pyroxenite and hornblendite are representd. Granite gneiss and gneissoid granite with indeterminate gradations. Mica and quartz and hornblende schists. Crystalline and silicated limestones. Banded injection gneisses and impregnated gneiss of confused relation. The chief geological problems are these two: first, to single out the principal fundamental units and map their general distribution ; second, to determine the relation of these units to one another and the origin of their petrographic variability. The structure of the region trends northeast and southwest Most of the formations fall into this structural trend in their own distribution. The principal control seems to be the original rock structure of the region itself, that of the Grenville. Even the fold- ing and faulting of later time conforms to the same orientation. Such deviation as there is, arises chiefly from two causes, namely, (1) portions of igneous intrusions which have not developed a gneissoid habit often do not maintain the simplicity of the general structural trend; (2) some faults of later date cut across this general structure. Illustrations of the former cause of irregularity are such masses as Dunderberg mountain and Bull hill, and representatives of the later faulting are the Mahopac flexure and minor faults. In some places the original northeast trend of the structure has» been so disturbed by large intrusions that it is now almost perpen- dicular to the normal direction. This may be seen at Fort Mont- gomery, where the principal structure for a short distance trends northwest and southeast instead of northeast and southwest. Method of mapping. On account of the obscurity of forma- tional boundaries the difficulty of mapping can not be fully over- come. It is impossible to draw sharp lines of demarkation between certain formations. A method which more nearly represents the actual conditions of affairs would be to map distinct formations sharply where they are typically and clearly developed and allow them to overlap in intermediate or transitional zones, so that the colors are mingled in that portion where it is believed the actual rock materials 28 NEW YORK STATE MUSEUM are mixed. Even this method has disadvantages because of the difficulty of determining how much is due to mixture and how much is due to original individual variation, but it will lead to much less error and confusion of interpretation than to draw sharp lines of separation. This method, therefore, has been adopted as suitable to the purpose of this particular study and it is to be understood that where the colors are single or simple, it is the authors’ judgment that the rocks are fairly distinct and distinguishable, but that where the colors overlap, the rocks are intermediate and probably mixed. Individual formations mapped. On the basis explained above, the following formations have been determined as mappable. A Oldest metamorphics 1 The Grenville series of metamorphis sediments (the oldest formation ). B_ The older great igneous members 2 An old injection or impregnation type of Diorste gneiss of uncertain relation to the other types except that it is inti- mately associated with the Grenville and is judged to be the oldest intrusive. This may be referred to as the Peekskill diorite gneiss or the Pochuck gneiss. 3 The Canada Hill granite and gneissoid granite with a multi- tude of variations. 4 The Reservoir granite and gneissoid granite, a xenolithic granite with many variations. 5 The Storm King granite and gneissoid granite with its injection borders. C Crystallines of doubtful relation and age 6 Lowerre quartzite, not occurring in this district in large enough development to map. (Apparently conformable with the Grenville structure) 7 Inwood limestone. A crystalline limestone. The same rock that forms the limestone valleys of southeast New York, south of the Highlands to New York City. 8 Manhattan schist. A mica-schist, undoubtedly to be cor- related with the extensive development of mica-schist overlying the Inwood limestone of the district south of the Highlands. D The Cambro-Ordovician series 9 Poughquag quartzite. (Clearly unconformable on the Highland gneisses) 10 Wappinger limestone. (Conformable to the Poughquag) GEOLOGY OF THE WEST POINT QUADRANGLE, NEW YORK 29 11 Hudson River slates and phyllites. (Conformable above the Wappinger) E Later intrusives belonging to the Cortlandt series 12 Norites and diorstic rocks of the principal Cortlandt area. 13 Peekskill granite and Mohegan granite (of Cortlandt series age). PETROGRAPHIC GEOLOGY — ROCK FORMATIONS This discussion is concerned chiefly with the following three items: (1) petrogenesis, (2) products of the geologic processes represented by groups of larger petrographic significance, (3) map- pable formations and their petrography. Petrogenesis It has already been indicated that a confusion of types is char- acteristic of the Highlands district. The whole range of rock types capable of being developed from original complex sediments and associated igneous intrusives with both an older and subsequent dynamic history is shown here. And the complexity was not devel- oped to its extreme in any one cycle. The history is bound up with successive igneous invasions, some of them very acid and others very basic so that an extreme range of composition is possible. Dominant types. The task of resolving this confusion into a group of dominant types at first looks hopeless. But a critical inspection with a microscope reveals the fact that there is, in most cases, a recurrence of a peculiar habit or a critical character which, when one has the clue, is recognizable. This suggests that there are certain traceable relations which have a broad application in the matter of relation and identity of formations. This is readily recognized in the simpler Hudson River-Wappinger-Poughquag series of Cambro-Ordovician age. It is less easily followed and one’s identifications become less certain in those formations of more complicated history, such as the Manhattan-Inwood-Lowerre series. The difficulty is so pronounced, in this case, that it is still a question what the true age of these members may be. The difficulty of working with the Grenville is still greater because of the excessive modification that this formation has suffered. The _ limestone is the only member of the Grenville that maintains even moderately well some decisive evidence of its former make-up, per- haps because it is less susceptible to impregnation by igneous matters. At any rate at many places the limestone can be readily found, but 30 NEW YORK STATE MUSEUM the limits and exact nature of the other members are very uncertain indeed. The igneous representatives are the most troublesorae of all, not because of the difficulty in distinguishing between the members, but because, if one is interested in the genesis of their variations, it is necessary to consider so many possibilities of origin. Because of the obscurity of some of these conceptions, it is thought best to discuss this matter at some length before the individual formations are described. Causes of variation in the crystalline rocks. The chief causes of variation may be listed as follows: 1 Original differences of composition in sediments. 2 Dynamic Metamor phism with recrystallization and deformation. 3 Original magmatic differences of the invading igneous magmas. 4. Magmatic differentiation within these igneous masses. 5 Magmatic movement with development of gneissoid habit. 6 Syntexis or magmatic absorption. 7 Igneous injection in its many forms of lit-par-lit banding, peg- matitic bunches, veins and dikes. 8 Igneous impregnation penetrating the grain of the original rock by extremely fluid and vigorous igneous matters, resulting finally in a mixed product which is in part original and in part introduced materials. These two causes (7 and 8) together give every possible gradation from one to the other and from both to the original invaded rock on the one side and to the invading igneous rock on the other. 9 Contact effects produced by igneous rocks on older rocks of all kinds. 10 Deformation which has resulted in the usual shearing, granula- tion, crumpling, recrystallization and schistosity. These are the usual causes of variation in ancient rocks of com- plex history, but it seldom happens that all of them are so exten- sively developed and displayed so magnificently as in the Highlands. After one has studied the region and become convinced of the major features of its geology, the formations, with all their apparent con- fusion, do not appear a hopeless mess, but show clearly the effects of a most interesting series of processes, an understanding of which adds immeasurably to their interest. Instead of being a confused jumble, they constitute one of the best exhibits of deep-seated, vigorous transformation processes to be found within easy reach of large centers of population within the borders of the United States. i Kt a ee ae: GEOLOGY OF THE WEST POINT QUADRANGLE, NEW YORK 31 A walk across the West Point quadrangle with an understanding _ of the geological principles represented in its great variety of rock structure and composition is a better exhibit of structural and dynamic geology than a whole museum of specimens. Some of the principles represented, however, are so seldom encountered that it seems to be advisable to discuss at greater length the different processes involved in the petrogenesis. Original differences of composition of sediments. This is clearly a possible cause of variation. The chief differences in the Grenville metamorphics doubtless depend upon this point. All the variety in the simpler metamorphosed sediments and much of it in the more complex ones is directly related to the variety of the original sediment with which the whole history began. Certain beds of particular composition have maintained their identity fairly well, others have recrystallized so as to be indistinguishable from similar rocks of very different origin, and still others have yielded to igneous attack to such extent as to have lost most of their original character, even their composition. Doubtless there were originally some thousands of feet of shales, sandstones and limestones in many repetitions and varjations of quality. It is these rocks that have imposed their composition and structural influence on all subsequent products. . Metamorphism. ‘There is hardly a formation in the region that does not show at some point the effect of dynamic metamorphism. The freest from it are the members of the Cortlandt series. Next to these are certain large granite masses of the Highlands belt proper, such as Storm King, Breakneck ridge, and Dunderberg mountain ; but even these are dynamically affected along certain zones to such - degree that the original character is wholly destroyed. All the sediments are extensively affected. The most modified of all is the most ancient sedimentary representative, the Grenville; next is the Manhattan-Inwood-Lowerre series and least of all the Hudson River-Wappinger-Poughquag. In the last group are occasional occurrences of shales and slates and beds of limestone and quartzite which maintain clear evidence of their original bedding and composition; but in many places the sedimentary structure is completely eliminated, the minerals are reorganized, the textural habit is entirely new, and even the com- position has been altered. The chief change probably is the elimina- tion of combined and interstitial water and soluble salts and the introduction of silica in the more open-textured beds such as the Poughquag quartzite. 32 NEW YORK STATE MUSEUM This is the condition of the simplest series on the northern margin of the quadrangle, but a long wedge of the same series occurring in the Peekskill valley region has been still more modified, so that the shale-slate member is there a phyllite, with bedding structure completely destroyed, the limestone member is crystalline limestone, and the quartzite is completely recrystallized. This, however, is the normal dynamio-metamorphic effect. There is, as far as the writers know, no reason to attach great importance to contact metamorphism of this simpler series. In the case of the mica-schists of the Manhattan-Inwood series, however, reorganization of the most elaborate sort has been accom- plished. A coarse-grained schistose rock has been developed which extends in repeated belts from the margin of this quadrangle to New York City and is injected and impregnated on a most elaborate scale. It may be taken to represent an intermediate type of metamorphic rock involving both dynamic and igneous influences. In many localities, the recrystallization effect is dominant and the other either insignificant or lacking, whereas in other places igneous influence and introduction have changed the character of the rock. Everywhere all trace of the original bedding is destroyed. Every- where all the original material has been recrystallized and great variety in quality and structural habit has resulted. It has often been held that the Manhattan schist owes its com- plexity, especially its extreme recrystallization, more to igneous ‘influence than to its dynamic history, and that the difference between the Manhattan schist and the Hudson slates is dependent upon this difference of field relationship. To what degree this may be true is discussed more fully under the topic Correlation. At this point it is sufficient to mention this additional cause of metamorphic com- plexity represented by these rocks. The most elaborately metamorphosed formation is the Grenville series of ancient sediments, which are limestone, schists and gneisses in their present condition. They are the extreme in the direction of metamorphism indicated above, where contact, injection and impreg- nation effects are dominant over the simple dynamic and recrystal- lization processes. It is perfectly apparent, however, that these rocks have been modified extensively by dynamic influences. Most of the dynamic history is believed to be earlier than the igneous intrusion, but there has been so much subsequent modification that it is not possible to discriminate between the metamorphic habit developed before any of the igneous rocks were present and that - 4 i i : GEOLOGY OF THE WEST POINT QUADRANGLE, NEW YORK 33 which is involved with the igneous history itself. It seems certain, however, that these rocks have derived more character from their igneous relations than from their earlier metamorphic history. On the whole, the simpler formations, such as the Hudson-| -Wappinger-Poughquag series, represent comparatively straight- forward dynamic history and the sort of metamorphism that belongs to recrystallization of rocks under no very enormous load. There is much distortion, faulting, dislocation and flow of the softer members and differential movement between the more competent ‘members, with the usual development of slates, crumpled phyllites, crush breccias and somewhat recrystallized limestones and quartzites. In contrast, the Manhattan-Inwood series represents most elabo- rate recrystallization under sufficient load to accomplish complete reorganization, and development of high density minerals such as garnet. Mica schist, hornblende schist, limestone schist, quartz schist and crystalline limestone of coarse marble habit are not unusual — apparently recrystallized under dynamic influence. This condition prevails even where igneous phenomena are not apparent and it is therefore believed that it is not necessarily con- nected with that influence. But it is, at many other points, associated with igneous phenomena which do give the effects already emphasized in this type. . In the older series, the Grenville, occasional members are little affected by injection and impregnation from igneous sources, but the formation, as a whole, is very extensively involved. There is much silication of the limestone with decarbonation and development of graphite already described. Original magmatic difference. The variations in rock quality caused by original differences of the invading magmas are not so great as those due to other causes, but there are differences of this sort and some of the peculiarities of petrographic quality are con- nected with them. It appears, for example, that certain of the magmatic units were exceptionally capable of invading the surround- ing or overlying country rocks in an insidious and pervading way so as to mix intimately and extensively with these older members. This is particularly true of the “Canada Hill” type of granite which, as interpreted by us, was capable of penetrating all the weak- nesses of the adjacent rock and introducing its own minerals, and also of absorbing great portions of this same country rock and incorporating it in its own magma. Sometimes, doubtless, nothing of the original has been preserved, but in other cases, something of 34 - NEW YORK STATE MUSEUM the rock which was being digested remains. Where there has been failure to redistribute much of this older material, it now remains | as abnormal constituents of the granite and also gives structures abnormal for a simple granite. These are more properly connected with syntexis, a topic to be discussed later, but are mentioned here as a feature particularly characterizing certain magmatic units. The result of the magmatic habit emphasized in the foregoing statement is to develop extensive and obscure granitic gneisses, the quality of which varies with the composition of the two original rocks and with the degree to which either impregnation or syntexis has devel- oped. Elaborate gradation should be expected, in connection with such a series, from simple dynamio-metamorphic sediments and simple granites through every possible proportion of intermixed gneissoid rocks. Other magmas appear to be somewhat less capable than the Can- ada Hill of penetrating or absorbing country rock, and as a result xenolithic blocks or remnants are more prominent along their borders. This difference in activity of the magmas is quite inde- pendent of any minor differences such as microscopic structures or mineral composition, although these do aid in distinguishing the individual units themselves. These small petrographic differences are, as a matter of fact, the most critical of all in identifying the different field units (see petrographic description), but they are not the cause of the variation of the series as a whole. It is possible, of course, that a magma might develop great varia- tion from causes such as differentiation and this is a factor to be considered, but the matter belongs to another discussion. When magmas are less vicious or vigorous in their behavior than those just discussed or when the intrusion takes place nearer the surface they cut other formations more sharply. When such magmas penetrate other rocks, they follow structural weaknesses already established instead of soaking through the entire rock. They develop complex structural features of lit-par-lit type and tongues or stringers and dikes of still sharper margins, but have much less capacity for impregnation or absorption of the surrounding rock or of reorganizing its minerals. The Storm King granite is of this type. It has marked tendency to the development of pegmatitic habit within itself and may have influenced overlying formations by sending emanations and similar products into them. In spite of its pegmatitic tendency the formation itself lacks some of the capacity of the earlier units to modify the adjacent country rock. GEOLOGY OF THE WEST POINT QUADRANGLE, NEW YORK 35 It was not sufficiently fluid and vigorous. This type of behavior seems to characterize the later units rather than the earlier ones, or it may be that the portion of the older unit now exposed, was not so likely to show this behavior. Such a habit might belong to the upper portion of a mass more prominently than to the deeper portions. The Cortlandt series as a whole is still less capable in this respect. Blocks of gneiss and schist involved in Mohegan granite are sharp- margined and not materially different from the rock at a distance from the granite, and the contact of the principal Cortlandt mass with the inclosing schist shows so little effect on either rock that typical specimens of the formations may be taken within a few inches of the margin. It appears, therefore, that magmatic differences in the igneous units have been important factors in producing some of the rock variety of the Highlands, and it is a distinct step toward a compre- hension of the meaning of the whole series and an appreciation of the genesis of some of these types to distinguish these different habits or capacities of different magmas. Magmatic differentiation. Every large igneous unit in this quad- rangle shows such continuous gradations within itself and the variety of facies is so great that it is difficult to escape the conclusion that magmatic differentiation is responsible for some of them. In the older and larger masses in particular, these gradations include wide divergence in mineral proportion or composition, difference in texture from medium fine to extremely coarse and difference in structure from massive to streaked or banded, or from uniform massive to bunchy pegmatitic and primary veined structure. Not every formation exhibits all these habits to equal degree, but all exhibit the tendency. The Peekskill or Mohegan granite undoubt- edly shows the least tendency in this direction, but even in it there are so many grades of color that the product of the quarries on a single property is assorted for marketing purposes into several grades. The variability shown by the Cortlandt series is explained more easily as a differentiation effect than as anything else. In this series norites, gabbros, peridotites, diorites and quartz-diorites grade into one another most intimately while dikes of syenitic or granophyric composition and even the Peekskill-Mohegan granite itself are judged to be differentiates of the same magmatic mass. This formation is less confused than are some of the more ancient granites, and its differentiates are readily distinguished as such. In the older mem- S 36 NEW YORK STATE MUSEUM bers the gradations and variations are more strikingly represented, but their origin as magmatic differentiates is not so certain. For example, the more vigorously penetrating members and those which were intruded during movement, as well as those which had strong pegmatitic tendencies, have a tendency to develop extreme differ- ences in very short distances. giving a structural habit more than a differentiation effect. Wherever the structure is massive or uniform, variation is also simple and gradual, but in portions with strong gneissoid structure or strong pegmatitic tendency, the differences are more abrupt and the extremes are much greater. Judging from the structures represented, it appears that deformation during certain stages of crystallization is not only an aid to differentiation, but a very prolific cause of pronounced complicated and variable structure. It is the writers’ belief that the movement represented is largely regional deformation rather than internal convection within the mag- matic mass and that some of the Highlands gneisses owe their chief structural habit to this process. Tlhey are therefore apparently not simple gneissoid granites but are in part dynamic and to that degree have many of the characteristics of true gneisses. That they have not been deformed or recrystallized to any considerable amount since complete solidification is practically certain, and it is absolutely certain that their chief structure is not due to recrystallization at all. To this degree, therefore, the rocks of this structural habit and rela- tion are more properly representatives of the gneissoid granites than of true gneisses. It should not be concluded from the emphasis placed on this process, however, that we consider this the method by which all the streaked and banded rocks were made. As a matter of fact, it seems to us that most of them have developed under quite different conditions and influences, with the aid of syntexis, injection, impreg- nation and structural control from the previously existing forma- tions. In other words, it seems to us that banded and other strong structures of the same general habit are in large part antecedent structures imposed upon the igneous mass and preserved in it even where the original mineralogy may have been destroyed. It is scarcely within the province of such a paper as this to dis- cuss the mechanics of differentiation and the different theories of the working of this principle, and we do not undertake to argue for or against the principle of liquation, or the separation of mag- matic liquids of different quality, as compared with the principle of fractional crystallization or the separation and settling of crystals in GEOLOGY OF THE WEST POINT QUADRANGLE, NEW YORK 37 solid phase. Perhaps both processes are represented. Perhaps the development of a pegmatitic facies is only the rejection of end- product matters from a partly solidified mass. To this degree, therefore, it is a result of fractional crystallization. It is also pos-- sible that some of the banding structure and gneissoid habit has a similar history connected with convectional movement or regional deformation during crystallization, and perhaps for some of the differences in the same structural unit one should resort to the principle of liquid separation as an additional factor. Processes “of some kind connected with the differentiation have brought about marked differences of composition within short distances and these, in conjunction with movements of all kinds, have caused at least part of the complex structural variety and petrographic confusion of the ancient gneisses of the Highlands. It is entirely possible, and indeed as we believe highly probable, that even the basic differentiates, represented by the hornblendic pegmatites and the magnetite ores, are related to one or more of the granites. If one makes allowance, therefore, for such extremes of composition it adds materially to the difficulty of drawing boundaries between formations in mapping, and it leaves one in much uncer- tainty about the proper correlation of many of the smaller field units. But, although it adds to the difficulty of clearly connecting individual specific occurrences, a recognition of these differentiation possibili- ties aids materially toward an understanding of the great complexity. And since the petrographic variation is so great anyway that it is impossible to make every variety a distinct unit, it leads to more successful understanding of the whole structure to give credit for some of the mineralogic variation and structural peculiarities to the process of magmatic differentiation. Magmatic movement. This topic has been discussed to some extent in connection with differentiation phenomena. It is sufficient at this point to review the item for the purpose of emphasizing its comparative importance. Even the simpler granites very rarely have perfectly massive structure. They are almost universally streaked or crudely banded in a way that suggests at once some form of flowage. In some cases such structure as the rock contains seems to have no necessary relation to the dynamic structure of the region, and it may be that these portions represent simply convectional movements within the magmatic masses. But by far the more com- mon structure is strictly conformable with the regional structure or trend and in so far as it is not derived from outside control through 38 NEW YORK STATE MUSEUM dissolved blocks, or is not an injection effect, it is induced by regional deformation acting on the magma during its later stages of crystal- lization. In some cases there are small crumples and wavy structure throughout a mass which could not be affected in that manner when solid. Again there are occurrences of pegmatitic facies of the same rock which cut squarely across these complicated structures and are not affected by them. This indicates clearly that the crumpled or wavy structure itself was developed before the rock had entirely finished its crystallization. For the pegmatites, which are the final products of the crystallization, would show the result of movement if they had been solidified at the time the movement occurred. Cer- tain portions of the Storm King granite as well as portions of other granites, occur in this manner, and it is believed to be more common than development of gneissic structure after complete solidification. However, deformation subsequent to recrystallization can not be eliminated as a cause of gneissic structure. It is very clear that there has been deformation, and there has been recrystallization even in some of the most substantial rocks, but for the most part these effects are either local or confined to the more incompetent members. There are few evidences of extensive recrystallization induced by regional metamorphism of the granites. Magmatic absorption or syntexis. It seems to us that an additional process of very large influence is syntexis, or the absorbing of country rock by invading magmas. Blocks of country rock have been included as distinct xenoliths and probably no competent observer would question either their abundance or their significance. It is also clear that such xenoliths may be found in practically all stages between that of almost complete independence and little modi- fied condition to that of almost complete destruction. It is probable, however, that not every one would be willing to believe as much as we do in the complete absorption of large quantities of wall rock, and to credit as much of the difference in quality within the igneous mass itself to this cause. But it may indeed be, that more of what appears to be a differentiation effect is really due to incomplete syn- texis, with failure to redistribute the different matters that have been incorporated, than to differentiation proper. It may thus happen that much of the streaked and banded structure and of the divergent compositions and qualities may be a sort of obscure preservation of the original structure of the rock masses absorbed. Such an effect might be called an antecedent structure in igneous rocks. It is neither a product of differentiation nor of movement, but a structure that GEOLOGY OF THE WEST POINT QUADRANGLE, NEW YORK 39 has been crudely preserved after the rock which it represents has been otherwise wholly destroyed; and it is a result of the failure to redistribute completely its chemical components rather than a peculiarly efficient assembling of them. It is believed that this principle is represented on a very large scale and, to some degree, in all the formations appearing as invading igneous masses. Even the Cortlandt series has its representatives of this sort, as advocated many years ago by the senior author of this bulletin in explanation of the meaning of the emery deposits and their peculiar structural and compositional features. The most striking representative of this habit, however, is, we believe, the type designated in this paper, the Canada Hill granite. This type, as already indicated in an earlier paragraph, seems to have been especially competent and vigorous, both as an insidious invader of adjacent country rock and as an absorber of incorporated blocks from the same source. The gradation is so complete in all stages between these two extremes of behavior that it is impossible to determine where the invaded rock, still retaining some of its old composition, stops, and the absorbed rock, representing a syntexis with nothing left but the so-called antecedent structure, begins. That both are largely represented we feel certain but the appearance is so similar and the structure and composition, even in minor detail, are so nearly alike that no adequate criteria have yet been discovered for their discrimination. Here again, an understanding apprecia- tion of a principle or process is a great satisfaction and aid in inter- pretation of the complexities encountered in the field, but accurate discrimination between individual specimens is often impossible. Igneous injection. It is well understood that certain very fluid types of igneous magmas show great vigor in invading adjacent rock, and seem to find all sorts of obscure weaknesses along which to thrust themselves. In a general way, even those magmas not strikingly capable in this direction are able to penetrate or cut through overlying or adjacent formations. In this sense, all the igneous masses in this quadrangle are intrusions, but only those of comparatively high fluidity succeed in penetrating vigorously enough to become distributed in small masses through long distances. Such a tendency normally develops a striking banded habit if the injections are repeated or occur at small intervals, and results in the so-called lit-par-lit injection structures. Such action is not con- fined, of course, to a single invading magma or to a single epoch, and in a district with as complicated a history as this, such injection 40 NEW YORK STATE MUSEUM processes might be repeatedly set in operation by succeeding mag- matic invasions. In such cases a rock would become exceedingly complex and even an ordinary museum specimen might represent not only the original country rock that preceded all the injections but additional material from each succeeding igneous invasion. Occasionally these individual portions are in large enough bands or are striking enough in their petrography to be correlated with their source. But in many cases it undoubtedly happens that differentia- tion of the invading fluid and its contamination by absorbed material together with recrystallization of some constituents have given a rock which is not readily assigned to a particular type. Clear cases, however, are so frequent that there is no doub* ot the importance of the injection process in the manufacture of the banded gneisses of the Highlands. It is our belief that the strongly banded gneisses are more frequently of this origin than of any other simple origin, that next to this process in the matter of competence to deveiop a banded structure is syntexis, and that differentiation proper is the least efficient of all. Injection phenomena are not difficult to under- stand and in many cases are readily recognized, but in many of the complicated gneisses of the Highlands the confusion is so great that it is impossible to indicate with certainty which structures are due to one type of origin rather than another. It is a process the understanding of which helps very materially toward an accurate working conception of the meaning of the geology of the Highlands, _ but in detail, in a minor way, the complete statement for every out- crop is absolutely impossible. Igneous injection is related to magmatic differentiation, to syntexis, to magmatic movement and to igneous impregnation and contact effects. These are as a matter of fact only the different expressions of the whole complicated process of deep-seated rock-making during igneous invasion. All the ancient granite magmas have developed injection phenomena, but it is more noticeable with the Canada Hill type, the older diorites, the Reservoir type and the Storm King. The Peekskill-Mohegan graniie and the Cortlandt norite series have had little injecting power. Igneous tmpregnation. We are using this term to distinguish insidious interpenetration of magmatic matters from the simpler injection type just described where, as a rule, the introduced material is distinguishable from the country rock. In true impregnation the material that is introduced is capable of entering the interstitial ‘SYIOI JO Solos SpuR]YySIFY oy} FO Sioqmoeut jue}10dtut du} JO 9914} FO SUOT}EJOI DY} So}JeA}SHI[I pue sjussotdet DIOFItIY} YOO] oy], ‘opueis [IPT epeue) YIM poziyt -UBIS SNYCIOWLOUI ][IAUSIN) FO SURI 91R suOTZIOd JOpjoO sy} pu ‘9}1UeIS ITOATISAY JY} 0} SuOTeq 0} paspnt SI Jo UU WOTDIfUL }so}v] OU, ‘[[P[sSyee_ Iku d}MUeIS JMOATOSAY FO Saspoy] UO suUTAT YDO}q VsoOoyT & St SIY TL, ‘sSloUs UOTJOOfur pezueLs Jopjo ue JO Uorjoofut o}ueIS di}WeUIdIG GEOLOGY OF THE WEST POINT QUADRANGLE, NEW YORK Al spaces between the grains of the older rock and of penetrating its most minute structural imperfections and, in extreme cases, of liter- ally saturating the original rock. In its simplest form this process resembles induration and silicificatton where materials are simply added. In its somewhat more elaborate form it is a selective replace- ment. In its most complicated development it is accompanied by absorption, by replacement and by contact metamorphic effects which transform the original rock into a mixed product. This is in part made up of remnants of former minerals, in part of syntectic products, and in part of materials that represent the invading ‘igneous masses. Doubtless very fluid condition and high content. of mineralizers or emanations, together with high temperature and great depth or pressure, are conditions favorable to such type of penetration. Certainly not all igneous masses exhibit any such tendency in their field occurrence, but some of them do and an occasional one exhibits this behavior to a very exceptional degree. The most efficient unit in the West Point area seems to be the Canada Hill granite. It has been mentioned before as showing competence.in absorbing the surrounding rock, but it probably was equally vigorous in sending out invading substances which penetrated the older Grenville series most complexly. It thus happens that it is impossible in some places to decide between the conflicting possibilities of rock origin, because the rock may be partly metamorphosed sediment and partly true igneous. These two representatives have so intimately intergrown that the rock is now as simple looking as some of the direct differen- tiation products or some of the metamorphics. The itypes of original rocks most readily invaded in this way seem to have been the granular fragmental ones or the shaly or schistose ones, but the effect is sometimes noticed even in the limestones, and it is not unusual to find an abnormal carbonate content in a rock that other- wise looks like a granite gneiss. Such rocks should be called grani- tized rocks if the invading substance is of granite composition, but there seems to be no general term for the process as applied to all magmas. Granitization, however, stands reasonably well for the results secured in this district, because certain of the granites give the most conspicuous examples of the working of the process. Farther to the south the same habit appears in connection with pegmatite development in certain portions of the Manhattan schist. These pegmatites have soaked through the schist in an almost unbelievable way and to such large amount that in places'the schist 42 NEW YORK STATE MUSEUM is more than half granite. That formation has not been so affected within this quadrangle but very elaborate granitized effects are pro- duced in what was once the Grenville. A peculiar form of this impregnation process appears in connec- tion with the Cortlandt series, where xenoliths were partly absorbed. It is believed that those are the places that have developed corundum, emery and spinel and are the sources of the emery deposits of the Peekskill district. The process of impregnating the original rock together with the selective removal of material from it has developed these unusual constituents. None of them appears in either the original schist or the original norite, but they are found where traces ef syntexis and impregnation are in evidence. ‘It is possible that other impregnation effects are selective in their nature, that in most cases part of the country rock has been com- pletely removed while new material has come in, and that the minerals finally left as the additional constituents are only a part of those which passed through the particular spot. Granitization of limestones is apparently a much more difficult thing to accomplish, and it is seldom observed in this or adjacent districts. Farther to the south in the Harlem quadrangle, however, where thin limestone beds are associated with gneisses, and where both injection and impregnation gneisses are developed, a case has been found where a limestone layer was transformed into a slightly banded granite gneiss, the change taking place within a distance of 30 feet. It is therefore difficult to escape the conviction that granite impregnation has been a very important process in the transforma- tion of many of the ancient rocks of this district. The older granites have apparently been the most efficient, and the youngest ones decidedly less so. The Peekskill-Mohegan type is practically free from important effects of this kind. Contact effects. In a district where igneous invasion has been developed on as large a scale as in this West Point area, one would expect to find some evidences of contact metamorphism. Such effects are found, but not on as large a scale or as clearly defined as other districts have produced. Perhaps it is somewhat more accurate to say that most of the contact metamorphism that has been effected is either so intimately involved with the processes already enumerated, or the connection of the metamorphism with any particular igneous influence is so obscure, that one feels uncertain about the amount of modification to be attached to this cause. To GEOLOGY OF THE WEST POINT QUADRANGLE, NEW YORK 43 a certain degree the process referred to above under the heading “Teneous impregnation” is a part of a series of effects usually assumed to belong to contact metamorphism. In so far as the materials introduced in this way combine with those already in the rock to make a new product, the classification holds strictly true,’ but in so far as the impregnation results simply in the penetration of the rock by the regular igneous rock minerals which crystallize there, it is a question whether contact metamorphism is a suitable term. The strong schistosity of certain parts of the Grenville suggest that regional metamorphism had accomplished a great deal, and that contact effects are supplementary rather than fundamental. If one includes injection and impregnation phenomena with the contact history, however, then certainly in many places contact effects are dominant, and original regional recrystallization of secondary impor- tance. But it is unlikely that the structural results now shown would have been attained if the older formation had not originally been schistose, crystalline and folded. As usual the limestone beds show the best evidences of contact metamorphism in this series, and extraordinary complexity of appearance and composition is a common development. Contact metamorphism of earlier granites and gneisses by later granite magmas.is very obscure and the later granites such as the Peekskill-Mohegan have little apparent effect. Even the xenoliths in this formation maintain their identity and appear to be of exactly the same character as adjacent rock of the same formation not thus exposed. The Cortlandt series accomplishes more on the xenolithic masses of schist that have been engulfed. Some are not only completely transformed in mineral constituents, but also show selective elimination and addition of material from both the original rock and the igneous host. Thus it happens that an abnormal com- position results with corundum, emery and spinel, none of which belongs typically to either rock. It is held by some geologists who have studied southeastern New York that the coarsely crystalline habit of the Manhattan schist, which differs so markedly in this respect from the Hudson River phyllite, is due chiefly to the influence of invading igneous matters or to subjacent magmatic masses which have induced more thorough crystallization. This view, therefore, would credit the highly crys- talline character of the Manhattan formation chiefly to influences that may be classed with contact metamorphism. The writers do 44 NEW YORK STATE MUSEUM not seriously question the competence of contact influences to accom- plish such differences of condition, or degree of reconstruction, but they doubt the appropriateness of the explanation for the crystal- linity of the Manhattan mica schist. In review of this point, therefore, it is proper to emphasize the fact that the usual silication and silicification or induration effects, as well as more elaborate and obscure recrystallizations, are in places evident and doubtless are of contact origin. This is not the only cause, however, of recrystallization, and it is therefore not always possible to specify to what degree the various schists, gneisses and limestones owe their present peculiarities of composition and struc- ture to contact metamorphism. Dynamic influences or deformation. It is not the purpose at this point to discuss the larger features of structural geology as dependent upon the deformation history, but rather to enumerate and compare the ways in which deformation has accomplished petro- graphic variation or modification. It is the writers’ belief that a very ancient dynamic history is responsible for the original structural quality of the oldest formation, the Grenville. It is our opinim that the deformation of that period developed foliated and folded rocks. The same influence is likewise in control of the petrologic quality of the Manhattan-Inwood series. To a much smaller degree also, a tendency to this same sort of development is to be seen in the Hudson River-Wappinger-Poughquag series. In connection with this deformational history, folding and fault- ing have resulted, the effects of which give some of the most strik- ing geologic features of the West Point area. In certain of the weaker members, fine crumpling habit is developed and similar struc- ture may rarely be seen in some of the gneissoid rocks believed to be essentially igneous. In the latter case it is believed to be due to deformation, perhaps of a regional sort, occurring when the rock mass was only partly solidified. We are not able to determine whether these dynamic influences referred to above as probably regional are connected instead with the crowding action of invading and intruding magmatic masses. Probably both have figured, but it seems to us that the regional influences are large and that the crowding and shouldering effects of igneous masses are probably comparatively insignificant. It is not clear, however, just how one could distinguish with certainty between them. The larger deformation movements have at times been concen- GEOLOGY OF THE WEST POINT QUADRANGLE, NEW YORK 45 trated in certain zones along which remarkable deformational effects are recorded. Some of the most elaborate transformations take the form of shearing, granulation and recrystallization (see plate 40) ; and where the conditions are not so favorable for this minute struc- tural effect, crush zones are developed with completely recemented crush-breccias. Such products have been secured from the Storm King granite, indicating deformation of this formation under rather ‘deep-seated conditions. All stages of dynamic disturbance are recorded in these rocks, from strain of the constituent minerals observable only in the microscope to completely mashed material. Recent experience in connection with certain engineering projects indicates that these strain effects are accumulated to great intensity along certain belts and that at considerable depth beneath the surface, in deep shafts and tunnels, these overstrained zones develop the peculiar “ popping rock.” This seems to be the result of the disturbed equilibrium pro- duced by removing part of the original support of the rock in these excavations. In such places new slabs break off along lines quite independent of the other structural lines of the rock and in the most pronounced cases add much to the danger and difficulty of deep underground working. (See discussion of Hudson River crossing in the chapter on engineering geology). The zones which have shown excessively strained conditions at depth are probably represented at the surface by the close-set parallel joints or sheeted structure that is repeatedly observed in all the massive rocks. A region where the most substantial rocks have such a condition irregularly distributed can hardly be considered to have reached any very high degree of stability. It is either accumulating additional strained condition, which may ultimately “overcome the strength of the rock and require readjustment, or else it is a remarkably well-preserved residue of much older dynamic impressions still held in the most massive rocks. Molecular read- justment is doubtless going on, but the normal resistance to such reorganization in the most massive rocks may account for all this lagging of deformation. Formational groups of larger petrographic significance The more important rock classes representative of the great variety which actually occurs are the following: a Sedimentary and organic rocks (little metamorphosed) b Sedimentary and organic rocks (much metamorphosed ) 40 NEW YORK STATE MUSEUM c Contact and metamorphic products of complex origin d Deformation products (shear schists) e Igneous types f Mixed types ‘The chief representatives in these different classes need little individual treatment because the mappable formations are discussed in the section immediately following. But as a matter of petro- graphic distinction, and as indicating the petrographic range of the district, it may be useful to make a preliminary list, noting separately the varietal types of each genetic class. a Sedimentary and organic rocks (little metamorphosed). This class includes a large development of quartzites, represented by the Poughquag formation, a larger development of limestones, repre- sented by the Wappinger formation, and a still larger development of slates and graywackes and more rarely of phyllites, represented by the Hudson River formation. All these are somewhat affected by metamorphism which has reorganized the original material more or less and developed new structural quality. This is least apparent in the quartzites and most prominent in the phyllites. Some of the quartzites are sandstones, but in places of greater dynamic distur- bance there is much tendency to recrystallization, the quality depend- ing upon the original make-up of the rock and the dynamic history of the particular spot from which it was derived. The slates are much more variable and range from simple fine black slaty shales to very siliceous and granular beds in which the material has been considerably reorganized, but which have no slaty cleavage. The slates are the most variable and show the dynamic influence more than the other types in this class. The phyllites are more completely modified from their original condition than any of the other rocks of this class. They represent metamorphosed slates and are found only in the downfaulted block bordering the west side of Peekskill Hollow creek valley and in the continuation of the same block on the west side of the Hudson at Tompkins cove. The most completely recrystallized limestones and quartzites are associated with the phyllites in this valley. A great variety of sedimentary representatives can be secured from the series. They are all of undoubted Cambro-Ordovician age. Simpler types than these are not known since no simple unmodified sediments except those of glacial and postglacial age occur within the boundaries of the West Point quadrangle. GEOLOGY OF THE WEST POINT QUADRANGLE, NEW YORK 47 b Sedimentary and organic rocks (much metamorphosed). This class is represented in the southeast quarter of the quadrangle, by the Manhattan-Inwood series, and by a strip of Grenville along the Hudson river, with occasional other smaller patches. It includes» thoroughly crystalline limestone or marble, recrystallized quartzite, and schists of great variety — chiefly mica schists, quartz-mica schists, and hornblende schists, all of which blong to the Manhattan- Inwood-Lowerre series. Gneisses of the greatest possible variety and associated schists and rocks derived from limestones are represented in the Gren- ville series. They include coarsely crystalline marbles, silicated limestones of great variety, banded gneiss and schistose rocks. It is impossible in this case to draw the line sharply between the sedi- ments that have been metamorphosed by the simpler processes and the contact metamorphic products of complex origin. As a matter of fact, they are close associates. c Contact and metamorphic products of complex origin. This class includes limestones that are thoroughly silicated and repre- sent typical contact influence and rocks that have been impregnated and injected by igneous materials. These rocks have been discussed in the earlier portions of this chapter. The products are chiefly ‘gneisses of great variety in quality and composition and structure. Garnet is often developed and doubtless many of the constituents are combination products representing neither the original materials nor the introduced materials alone. In this class is still greater variety in minor ways than in any other of the groups listed, but all have the complex metamorphic type of origin. This class is represented by the banded and streaked rock common ‘in the Highlands and is the basis of the term often used — the High- lands gneisses. It is still more typical of the Fordham gneiss, which is the name used in the New York City area. d Deformation products. Along lines of weakness or deforma- tion zones, particular qualities are developed which are found nowhere else in the region. These are directly the products of deformation and include shear schists and granulation gneisses. The particular quality depends on the rock originally involved and on the extent of the deformation and the balance between purely mechanical effects and recrystallization. There is, of course, no great areal extent of such products and none is mappable, but they form beauti- ful petrographic varieties of much interest. 48 NEW YORK STATE MUSEUM e Igneous rocks. These occur in great variety, and represent either plutonic or large intrusive masses or small dikes or veins. No surface flows are represented in this field. The acid type includes granite, alaskite and aplite. _ The intermediate type includes syenite and syenite porphyry. The medium basic rocks include diorite, norite, quartz-diorite and camptonite. The more basic group includes gabbro norite, pyroxenite and dunite. Each principal type of rock is represented in the field by numerous facies covering a wide range of mineral proportion and habit. The actual number of varieties would be very great. The most variable differentiates are pegmatites varying from sim- ple quartz pegmatite to hornblende rock and magnetite ores. Some of these occur as veins, some as dikes and some as injections and impregnations. f Mixed types. Mixed types are in part listed under d, but they include certain ones not mentioned there, especially the syntectics, which may appear as granite gneisses or gneissoid granites, the injection gneisses which are usually strongly banded, and the sili- cated metamorphics, chiefly represented by the Grenville series and xenolithic masses. The Mappable Formations with their Petrography The formations discussed under this heading occur in large enough development to require representation on the areal map. The chief bases of delimitation are: (a) unity of origin, (b) like structural or field relations, and (c) petrographic constancy. But in some cases the petrographic variety is so great within a single unit that this last principle of identification alone would not suffice. On this account, the mapping of the region is difficult. The for- mations themselves have great obscurity and exceedingly great com- plexity as indicated in the preceding discussion; these conditions make the problem of dividing them into definite units for mapping, more or less uncertain. The result is a generalization, necessitated by the limits imposed by the map itself. Small differences can not be mapped on a moderate scale; only the large divisions considered of primary importance can be taken into account and indicated. It has been necessary, therefore, to study the region with the object in mind of determining those characteristics indicative of the history of each formation and to apply them as well as possible / GEOLOGY OF THE WEST POINT QUADRANGLE, NEW YORK 49 to the delimitation of formations. These characteristics are dis- cussed below. The units that deserve discussion on this basis of unity of origin are described in some detail in the pages that follow. The Grenville series. The Grenville beds are the dominant type ~ in a belt about 2 miles wide along the Hudson river from Fort Mont- gomery to Cold Spring. There are good exposures along the New York Central Railroad from Garrison to Manitou (Highland station) and along the West Shore Railroad north and west of Fort Mont- gomery, along the Garrison cut of the Catskill aqueduct, and on the state road between Nelson Corners and McKeel Corners. The series is made up primarily of calcareous, micaceous and quartzitic beds which weather easily. Consequently this formation tends to form depressions, except where granitic intrusions have hardened it. The Grenville is the oldest formation in the Highlands and there- fore has suffered all the dynamic disturbances of the district, and is cut by all the intrusives. As it was initially a series of impure limestones, shales and sandstones the resulting product is of very complex composition. It would be impracticable to discuss all the varieties of metamorphic rocks produced, but the major processes involved are treated elsewhere in this bulletin and some of the more typical rock representatives are described below. In the outcrop the formation commonly shows as a series of banded, crumpled and distorted rocks which weather characteristically to a mottled black or a rusty brown color. The decomposing mica (phlogopite) adds streaks and patches of a peculiar greenish yellow so that the whole complex has an appearance markedly different from that of any other formation of the quadrangle. The massive limestones weather white, with the more resistant silicates standing out in yellow to brown or greenish lumps above the surface. The color of the weathered surface, and the graphite, serpentine or tremolite always present are sufficient field criteria for determination of this series. The disturbed condition of the beds along the Hudson river is probably a local deformation, as the Grenville seen along Sand Spring brook and Round hill is rather massive and blocky. Types of Grenville. Some of the characteristic types of the Grenville are described more fully below. Type a. Diopside-quartz rock. This is a dense, hard, light-colored, greenish gray rock. It is a rather fine-grained aggregate of greenish pyroxene crystals in a 50 NEW YORK STATE MUSEUM quartz matrix. There are minute specks of brown titanite and of pyrrhotite and occasional coarsely crystalline patches of dull-green pyroxene with large grains of pyrrhotite. Another variety of this rock is composed chiefly of grains of colorless pyroxene, probably diopside, with rather simple noninterlocking boundaries. The interstitial spaces are filled with an aggregate of zoisite, quartz and carbonate which appears to be secondary. Small rounded tit- anite grains are abundant. There is an occasional pyrite or pyrrho- tite grain. Type b. Quartz-epidote-schist. The rock is a dense, siliceous, fine-grained schist with alternating crumpled yellow-green and dark-gray bands. It is a fine-grained, quartz-epidote schist, showing granulation of the epidote. Interstitial spaces and lines of weakness are filled with quartz. The quartz bands show considerable contortion, but the quartz is not granulated. It has rather the appearance either of vein quartz or of having been introduced while the rock was being sheared. This deformation effect is still more strongly exhibited in thin section than it is in the hand specimen and it is from the microscopic examination particularly that the suggestion has been derived that the deformation represented is in part older than some of the in- jection material. (See accompanying photomicrograph, plates 4 and 5.) _ Type c. A graphitic diopside rock. A light-gray, hard, rather coarse-grained rock made of a gray pyroxene and flecked with shining scales of graphite. The rock is coarse-grained, made of slightly clouded diopside and graphite. It must have been developed by metamorphism from a carbonaceous limestone. Both regional and contact effects are prob- ably present in this rock. Type d. A silicated limestone. The rock is a limestone, very much sheared so that the calcite is not coarsely recrystallized, but retains all the effects of strain. It contains some quartz and a few diopside grains, iron-stained along the twinning bands. Type e. Serpentinous limestone. Rather massive, serpentinous limestone, of variable texture, _ specked with pyrrhotite. The rock is a medium-grained limestone with large, rounded, ser- pentine aggregates pseudomorphic after olivine. Small chalcopyrite veinlets cut the calcite. Plate a Photomicrograph of specimen no. 100-b. A shear-zone schist. Taken with plain light, magnification about 30 diameters. A specimen of Grenville epidote schist from a shear zone. Taken to show the fine structure of this rock with the minor crumpling and augen or mortar structure characterizing this material. The composition is chiefly epidote and quartz. Photomicrograph of no. 100-b-7.. Same as 100-b. With crossed nicols, magnification about 30 diameters. Taken particularly to show the detail of minor structure within the quartz bands of the same specimen 100-b. This is vein quartz probably derived from the invasion granites, and the epidote and other constituents are products of anamorphism under the same influences. These points suggest deformation of about Canada Hill age. Photomicrograph of no. 143. Grenville gneiss. Taken with plain light, magnification about 30 diameters. Quartz-biotite-garnet-gneiss. Taken to show the habit of the rock and especially its content of garnet. The constituents are quartz, crthoclase and acid plagioclase (all clear and smooth in this photomicrograph), biotite (dark gray and black plates), and garnet (gray rough grains). GEOLOGY OF THE WEST POINT QUADRANGLE, NEW YORK &t Type f. A garnetiferous gneiss. Medium to fine-grained foliated quartz-feldspar-biotite rock, spotted with large half-inch garnet-biotite patches, intergrown with sillimanite needles. The essential minerals are coarse red-brown biotite, garnet and plagioclase. Accessories are magnetite, zoisite, microcline, yellow brown hornblende. The biotite and plagioclase grains are bent. The biotite is oriented and interstitial. The garnet is confined to large spot of very coarse-grained garnet and biotite, which is the same as that in the groundmass. (See accompanying photomicrograph, plate: 6.) Type g. Graphitic amphibolite. A dark-green, coarse-grained foliated rock, composed almost entirely of chloritized uralite and graphite. The foliation is pro- duced by bands of different widths which apparently were originally amphibole and pyroxene. Some of the Grenville rocks are not so abnormal in composition as those noted above. Most of them, however, are schists of some description unless they are heavily impregnated with minerals of magmatic source. Such a schist is shown in the photomicrographs of no. 511 (plate 7) which is a mixed schist. Impregnation and injection and absorption products occurring in the same formation show a still greater variation such, for example, as that exhibited by the photomicrograph of no. 512 (plate 8) which has some of the earmarks of igneous addition. As a matter of fact, it is probably chiefly igneous representing some extreme of differentiation or selective injection whose source is believed to be the so-called Pochuck diorite intrusive member. - Those portions which are gneisses rather than schists are less striking in microscopic features, but all tend to exhibit suggestive content, such as the photomicrograph of no. 301 (plate g) which is a sillimanite gneiss, or the hornblende-biotite gneiss represented by no. 501 which is probably impregnated with Pochuck diorite. (Plate to.) ! The older igneous series. Pochuck diorite. It is judged that the oldest igneous representative distinguishable in the area is _ essentially a diorite. In this quadrangle it is practically always intimately associated with streaked and banded varieties of rock of the character belonging to Grenville metamorphics. It nearly always has the appearance of a gneiss and the composition, although very variable, includes hornblende, pyroxene and plagioclase feld- 4 52 NEW YORK STATE MUSEUM spar as the dominant constituents. The occurrence of pegmatitic facies is judged to support the interpretation given that igneous injection and impregnation of the original Grenville sediments by a magma of dioritic composition has been responsible for all of these effects. In some places it varies even to the composition of a soda granite. In its simplest form, however, the rock presents the appearance of a somewhat modified diorite, medium to somewhat basic plagio- clase is prominent, augite and hornblende are usually both present and the other constituents vary greatly. Generally the relation of this igneous member to other igneous representatives is obscure. The somewhat more intimate penetra- tion of the diorite and the comparatively clear-cut relation that cer- tain of the granites bear to this diorite gneiss supports the con- clusion that the diorite invasion was the earliest of all (see mixed types, p. 57, for additional detail). Canada Hill granite. The Canada Hill granite, as exposed typically at Kings quarry south of Garrison, is a medium gray, medium-grained rock varying from faintly to very perceptibly streaked. It is composed of white and gray feldspar, gray quartz, small crudely oriented biotite crystals, and numerous small, rounded, violet-red garnets. There is also a pegmatitic facies which is coarser-grained, grading into true pegmatite. It is penetrated by or streaked with white segregations of quartz and feldspar, resembling alaskite, carrying large patches of red-brown garnet aggregate. The weathered surface is dull gray. The feldspar and biotite weather out leaving the quartz and garnet. The new fracture in the weathered rock has a faintly pinkish or yellowish tinge. The mica is bleached yellow and carries rutile, the feldspar is rather chalky, and the gray quartz and dull-red garnets stand out clearly. This type represents the oldest and most vigorous of the granite magmas which have invaded the ancient complex of this district. Microscopically the rock varies greatly. On the whole, however, it is medium grained with remnants of dusty looking orthoclase as a prominent constituent with much fresher looking microcline with soda feldspar comparatively common, and abundant reddish brown biotites carrying numerous oriented rutile needles. Quartz also is a prominent constituent. A characteristic appearance and composition is shown by no. 440 (plates 11 and 12). Photomicrograph of no. 511. Grenville from east side of quadrangle. Taken with crossed nicols, magnification about 30 diameters. Showing a typical very complex make-up and comparatively fine grain. ae @ Quartz — abundant (clear). 6 Plagioclase feldspar much less abundant (clear). c¢ Biotite very abundant (gray plates with cleavage). d Hornblende, abundant (dark). e Titaniteabundant (very rough, small gray grains). jf Magnetite (a little) (black). small grains). Plate 8 g Apatite (high relief, clear an‘J Photomicrograph of no. 512. Injection facies of Grenville from east side of quadrangle. Probably a Pochuck injection product. Taken with plain light, magnification about 30 diameters. Showing a rather massive type with abnormally high apatite content. a Biotite abundant (dark smooth and in plates). 6 Hornblende abundant (dark with coarse cleavage). c Apatite abundant (high relief, colorless grains in the hornblende and elsewhere). d Quartz (few clear grains). ge Pyrite (large black grains). f Titanite (very rough). g Magnetite (a little) (black). NS Photomicrograph of no. 301. Grenville gneiss. Taken with plain light, magnification about fae! 30 diameters. : ed : : , al Taken to show a specimen of quartz biotite sillimanite gneiss. The constituents are quartz and feldspar (light smooth areas) biotite (black) sillimanite (light high relief rods). Plate 10 Photomicrograph of no. 501. An injection facies of Grenville from east side of quadrangle. Probably largely Pochuck diorite in present make-up. Taken with crossed nicols, magnification about 30 diameters. Showing: a Gneissic structure. b Abundant plagioclase (banded). c Abundant hornblende (dark and rough with cleavage). d Abundant biotite (dark mottled with cleavage). e Much less abundant quartz (clear). f A little magnetite (dead black). Plate 11 Photomicrograph of no. 440. Canada Hill granite. Taken with plain light, magnification about 30 diameters. Showing the typical habit of the Canada Hill type of granite: a Dominant feldspar, showing plainly in the field because of slight sericitic alteration (gray grains). 6 Prominent quartz (clear, neatly equidimensional grains). c. Biotite fakes with prominent sagenite structure of crossing Tutile needles (black in this reproduction). This rutile content and the slightly modified appearance of the feldspars is a very characteristic mineral habit of the Canada Hill type. Plate 12 _Photomicrograph of no. 450-b. Canada Hill granite from Kings quarry. Taken with crossed nicols, magnification about 30 diameters. Taken to show the distribution of feldspar and quartz constituents and the general structure of the rock. The chief feldspar is microcline. Quartz occurs in small irregular grains. Buiotite is in oriented plates. Three crystals of garnet occur in this field (black in this light). ; GEOLOGY OF THE WEST POINT QUADRANGLE, NEW YORK 53 _ Reservoir granite.- The Reservoir granite is one of the most ridely distributed granites of the Highlands. It is this rock together vith the Canada Hill type which has done most of the granitization f the Grenville. It is commonly found penetrating and invading ‘reservoir where the granite can be seen to be an igneous rock intruding the gneisses. A smaller exposure showing the rock type fairly well is at the bridge across Conopus creek, east of Dennytown. It is a rather coarse-grained, gray, gneissoid granite. At first sight a appears to be a true gneissoid granite, showing marked flowage effects, and cut by numerous pegmatite and quartz stringers. The ‘pegmatite is much crumpled and distorted, but the quartz cuts straight through all the other structures. On further examination large included blocks of dark, banded gneiss are seen. They are ‘crumpled and distorted and contain within their margins all the observed pegmatite. .They are in reality in all stages of assimilation and grade from almost angular pieces with distinct outlines to pieces ‘so completely dissolved in and penetrated by the granite that they ‘would be indistinguishable from it were it not for the pegmatites which remain unaffected. In the partly dissolved pieces there is a perfect transition from gneissoid granite to gneiss and the flow structure of the granite is in every case parallel to the original ‘crumplings in the gneiss. The granite is therefore a syntectic. The ‘structure is not its own, but is imposed by the invaded gneiss. (See ‘discussion of the processes of petrogenesis, especially syntexis, ‘impregnation, and the development of internal structural habit, page 29.) The typical Reservoir granite as exposed at Boyd Corners reser- ‘voir has a rather coarse texture of white feldspar striated and unstriated, and a very little quartz, and is strongly marked with oriented streaks and patches of deep-brown mica. It is spotted with the same small purplish to dull-red garnet as the Canada Hill granite. It has a tendency to break roughly along the mica planes, giving a mottled appearance to the rock. It varies from this to a finer grained, more definitely banded rock, produced by shearing. There is, even at the reservoir, a slight tendency to the development of the pink feldspar which becomes in the Mahopac granite a promi- nent constituent of the rock. It differs from the Canada Hill granite in its higher biotite content, and in the greater continuity of the mica bands. But the mica content is not constant and some speci- mens are difficult to distinguish from the Canada Hill. 54 NEW YORK STATE MUSEUM In thin section it is seen to be a medium-grained granitoid rock composed of orthoclase, acid plagioclase (albite and oligoclase), — quartz, biotite, epidote and zoisite, and in some specimens a blue soda | amphibole. The accessory minerals are apatite, garnet, muscovite, — titanite, rutile in the form of sagenite, and rarely allanite. The peculiar habit of the feldspar serves to distinguish this from — the other rocks of the region, especially in these two points: ) 1 They are extremely poikilitic and contain countless small inclu- sions of zoisite and mica which vary in size from a fine dust to clear, well-formed crystals. : 2 The feldspars show strong granulation of the edges of the crys- _ tals (mortar structure). In some cases the entire crystal has been broken up. Part of the quartz shows this effect, the rest of it with the biotite and epidote, occurs undisturbed distributed through the interstitial crushed feldspar material and along the crush lines. The foliated appearance of the rock is caused by the orientation of the mica. The quartz which has not been crushed is of the vein type with marked wavy extinction. The biotite is of a greenish brown color, not strongly pleochroic. It is occasionally intergrown with mus- covite and frequently with epidote. It occurs in two generations, as inclusions in the feldspar and as a late product of crystallization. The epidote or zoisite is variable in amount and character. It, like the biotite, occurs in two generations—a fine inclusion in the feldspar, and a coarser grained associate of the interstitial biotite and quartz. The garnet is in medium-sized grains, of a faintly pinkish color, in rounded but poorly developed crystals. Some of these characters are shown well by the accompanying photomicrographs. No. 430-a (plate 13) is taken to show the prominence of the zoi- site grains referred to in the general description. No. 332-a (plate 14) shows a typical granulation effect. No. 16-b shows a case where strong schistosity is developed in addition to granulation (plate 16). No. 430-b (plate 15) is another variety with both garnet and allanite. Mahopac Granite. The rock is a medium-grained, pinkish, gneiss- oid granite, distinctly but not strongly foliated. It is made of color- less quartz, slightly pink feldspar, and dark biotite. | The biotite is in rather fine bands, more abundant than in the Canada Hill granite, Plate 13 Photomicrograph of no. 430-a. Reservoir granite. Taken with plain light, magnification about 30 diameters. Taken particularly to show a prominent feldspar area with orthoclase and soda plagioclase, a small amount of quartz and biotite with very complex development of trains of zoisite particles in parallel and crossing streaks following former fractures and weakness lines through all of the feldspars. : Tetothier slides some of the rock is granulated. In this there is very little if any granulation, but very prominent development of these trains of inclusions. Plate 14 Photomicrograph of no. 332-a. Reservoir granite. Taken with crossed nicols, magnification about 30 diameters. Showing large plain fresh biotites cutting and distributed through a very finely granulated feldspar and quartz field. The principal constituent is feldspar, next in abundance biotite. The others are quartz and green hornblende and epidote. Photomicrograph of no. 430-b. Reservoir granite. Taken with plain light, magnification about 30 diameters. ; Same as last slide with a different field to show other characteristic make-up. The minerals are: a Large areas of soda-feldspar. 6b Many small grains of quartz. c Many large and small flakes of biotite. ad A very large grain of allanite. e A garnet area of irregular outline. f Very _ small amount of zoisite and other accessory minerals. Plate 16 Photomicrograph of no. 16-b. Reservoir granite. Taken with crossed nicols, magnification about 30 diameters. _ Slide shows a field with an unusually strong schistose and granular habit. The structural quality in this case is emphasized by the streaks of finer material, the granulation of some of the more brittle material and the orientation of the mica flakes developed along lines of weakness even cutting some of the other grains. The principalconstituentsare: a Soda-feldspars and orthoclase. b Quartz, mostly in aggregate form. c¢ Biotite, mostly oriented. d Epidote, zoisite and small amount of other minor constituents. The structure is the most characteristic thing about this field. GEOLOGY OF THE WEST POINT QUADRANGLE, NEW YORK 55 but much less so than in the Reservoir granite. The cleavage is therefore not as distinct as in the Reservoir granite. The Mahopac granite shows in thin section a combination of the characteristics of the Reservoir and Storm King granites. It has the marked perthitic growth which is the most constant feature of the Storm King, and also the intensely pleochroic biotite. The granulated edges of the feldspar, the later simultaneous introduction or development of the quartz and biotite, and the accessory mus- covite show resemblance to the Reservoir granite. These characters are considered critical and the rock is therefore judged to be essen- tially a facies of the Reservoir type. It may even be that this is a more fundamental or less abnormal type than the Reservoir, but in any case it seems to belong to the same invasion. The peculiar zoisite inclusions of the Reservoir granite are lacking, possibly because of the lower lime content of the country rock absorbed by the Mahopac magma. This is also shown by the feldspars which are chiefly perthite and microcline. Megascopically the granite appears to be an intermediate type. It is a light pink gneissoid granite which looks very much like the Yonkers gneiss of the Tarrytown quadrangle. It is a more distinct field unit than the Reservoir and not so distinct as the Storm King granite. | This granite is therefore petrographically a transition variety between the Reservoir and Storm King granites rather than a clear- cut independent type, and it is therefore difficult to locate accurately. The country southeast of Peekskill Hollow creek, bounded on the south by Peekskill creek, the Peekskill granite, Osceola lake, and Lake Mahopac, has this granite as its chief intrusive. The best exposures are along the road running from Kent cliffs to Mahopac ‘mines, especially on the fault scarp north of Mahopac mines, and also in the hill north of Peekskill in contact with the Poughquag quartzite. The Peekskill Hollow boundary is a sharp one, as here there is an unconformity and the Cambrian quartzite is laid down on the old eroded granite surface. The contact with the Reservoir granite is not at all clear. The best evidence as to the character of the con- tact is shown on the Kent cliffs-Mahopac mines road at a point just off the edge of the quadrangle. Here a pink granite dike with indefinite boundaries lies in contact with the gray, granite, and little wavering stringers of pink penetrate the gray blending with it. The rocks are evidently of approximately the same age. The resem- 50 NEW YORK STATE MUSEUM ee ee ee blance between the Mahopac and the Storm King granites is chiefly mineralogic and is most apparent in the microscope. (See plate 17 for microscopic appearance.) . Although it would be possible to map this granite separately, it | was finally decided on the grounds of its evident close relation to the Reservoir type, to consider it simply a facies of that invasion and include these together as one map unit. Storm King granite. The Storm King granite is a medium to coarse-grained rock, rather dark colored, slightly greenish.and some- times greasy looking, with a marked but crude gneissoid structure. The feldspars are gray or red, the quartz is gray, and there is strong black streaking of hornblende or augite. Biotite is not abundant. Garnet occurs more in the marginal portions of the mass and is probably produced by absorption of the invaded Grenyille. The quartz content varies from that proper to a normal granite to very low, so that a considerable portion of the rock approaches the composition of syenite. High quartz content and red feldspar commonly occur together. The pegmatitic phase is a distinctly red granite, very coarse-grained and not at all gneissoid, with lower ferromagnesian content than the main mass of the rock. In thin section it is a coarse-grained rock with good granitoid structure. The characteristic features are (1) intense pleochroism of the biotite and hornblende which turn from green and light yellow-brown to almost black, (2) abundance of microperthitic intergrowths. The essential minerals are quartz (in some specimens), perthite, microcline, oligoclase, biotite, hornblende, and light-brown augite in the darker varieties. The accessories are a little garnet occasion- ally associated with the hornblende, rather rounded zircon, apatite and magnetite. Allanite is rare. The magnetite appears in grains and also along the cleavages of augite (plates 18 and 19). The rock is fresh with no evidence of alteration except slight sericitization of some of the feldspar, and development of chlorite small, usually not over 5 or 6 feet wide. They are the latest of the sort caused by regional deformation, but strain effects are well shown in the quartz and feldspar. Crush zones, although rare, are known in this formation. Some of them are so completely healed as to form perfectly solid rock. Basalt, Diabase, Diorite. The basic dikes of the Highlands are small, usually not over 5 or 6 feet wide. They are the latest of the Precambrian rocks, cutting all the others, and are themselves quite Plate 17 Photomicrograph of no. 479. Mahopac granite. Taken with crossed nicols, magnification about 30 diameters. Taken to show a characteristic field of this type. Note particularly a Large microcline grains oa b Numerous granular aggregates of quartz | c Little biotite d Very small amount of accessories } The rock as a whole is characterized by rather large feldspars, chiefly microline with occasional very slight perthitic development. There is little biotite and a very large amount of quartz which is distributed in grouped | aggregates interstitially, and in isolated grains in lesser amount, and also in very minute amount intergrown micrographically with feldspar. Plate 18 Photomicrograph of no..187-b. Storm King granite. Taken with plain light, magnification about 30 diameters. 3 = é Taken to show the distribution of ferro-magnesian minerals in the rock and the development of perthitic habit. ; Dede The minerals are: Quartz (clear), perthitic feldspar, hornblende (dark rough grains), biotite (dark smooth flakes). Plate 19 Photomicrograph of no. 187-b-x. Storm King granite. Taken with crossed nicols, magnification about 30 diameters. : : é A different field of the same slide as the previous one taken with crossed nicols to show better the micro-structure of the rock, especially the microperthite habit and microline and the strained condition. 4 : : The minerals are quartz, perthite, acid plagioclase, microcline, hornblende and zircon. GEOLOGY OF THE WEST POINT QUADRANGLE, NEW YORK 57 _ unmetamorphosed except locally in certain shear zones. One of the simplest and least modified of this type is no. 115 (plate 20), a _ basalt. : The rock weathers to a buff color. The fresh fracture shows a dense rather dark greenish gray surface, felsitic to finely crystalline with occasional fine-grained, roundish pyrite aggregates. In thin section small feldspar and olivine pseudomorphs can be seen. The olivine is completely altered to serpentine. The rock is cut by many small intersecting veinlets of zoisite and serpentine. ' Many dikes also cut the Storm King granite in Breakneck ridge and the adjacent gneisses of Crows Nest and neighboring ground. The rock here is coarser and it has more nearly the habit of a diorite than of any other type. Some may have been diabasic. As a matter of fact, they show considerable variety. They cut the Storm King granite but do not cut the Cambrian quartzite in any case yet observed. Peridotite or dunite. A curious rock which may be related to the diabases is the dunite exposed near Tompkins hill. It forms a small hillock which is cut by the road and is surrounded by gneisses or granite. The contact is drift-covered. It is a fine-grained rock, weathering buff colored. No phenocrysts can be distinguished. In thin section it is seen to be an almost pure olivine rock, with a few magnetite grains. There is slight serpentinization which gives a faint silky luster to the fractured surface. This rock (no. 57) is illustrated by a photomicrograph (plate 21). Mixed types. Under this head are listed a few typical represent- atives of a very large group of rocks which are less constant in their petrography than those just described. In most cases they are judged to be either mixtures such as syntectic products, or they are impregnation effects or injection on a microscopic scale or they are extreme facies of the types just described. Perhaps some belong to units of still a different connection not prominent enough to be mapped independently. Only one in this list, however, is considered of enough independent prominence to be indicated on the map and this is the hornblende gneiss which, if there is a representative in this district at all, must be the equivalent of the Pochuck forma- tion as described in New Jersey. All the others are included in map- ping with the major units in which they are involved. a@ Hornblende-plagioclase Gneiss (Pochuck). Hornblende-plagio- clase or pyroxene-plagioclase representatives are common in small and scattered development or so involved with other kinds of 58 NEW YORK STATE MUSEUM material that they can not well be treated as a separate member. The most pronounced occurrence of this sort is in a belt beginning at Peekskill and extending in a somewhat broken way toward the northeast and again in the vicinity of Oscawana extending also somewhat brokenly toward the northeast. The most distinctly indi- ‘vidual occurrence is at Peekskill, where a belt about tooo feet in width lies between simple Grenville on the one side and a granite on the other. Undoubtedly these hornblendic plagioclase rocks are related to the Pochuck diorite type in origin and, wherever they can be sep- arately mapped, they should be indicated as Pochuck gneiss. This can be done at a few places such as the belt at Peekskill extending to the northeast, but a much larger number of occurrences are on such a small scale and so intermixed with material judged to be of other sources and relations that they have not been separately mapped. This is particularly true of considerable areas toward the east side of the quadrangle where the hornblendic varieties of rock are abundantly intermixed with remnants of the Grenville. We have indicated a large area as Grenville mixed with granite but have not found a way of indicating its Pochuck intermixture in all cases. : This rock carries a large proportion of either hornblende or pyroxene or both, usually also biotite, an abundance of plagioclase and varying amounts of quartz. The accompanying photomicrographs illustrate the normal appearance. (Plates 22, 23 and 24.) b Magnetite schist. Some of the finer grained rocks which carry magnetite in considerable portion have the general appearance of schists, but microscopically they show little foliation habit. The con- stituents are generally pyroxene, sometimes hornblende, abundant quartz and feldspar and magnetite. The proportions vary greatly and accessories are sometimes prominent, especially apatite. They are usually impregnation and replacement products representing a phase of igneous invasion. The general structural habit and mineral relation is shown in the accompanying photomicrographs. (Plates 25 and 26.) c Quartzitic gneiss. Occasional occurrences of very limited extent have the hand specimen appearance of recrystallized quartzites and were at first marked so in the field. Microscopic examination shows that they are not by any means so simple and are evidently not quartzites at all. Instead they are judged to be extreme differentia- tion products of some injection unit high in quartz. (Plate 27.) Plate 20 Photomicrograph of specimen no. 115. Basalt. Taken with plain light, magnification about 50 diameters. Taken to show the fine felsitic ground mass habit of this rock with its slightly porphyritic texture and its rather numerous rehealed fractures. The rock is not recrystallized and not sheared, but it is fractured and rehealed and somewhat altered. Photomicrograph of specimen no. 57. Dunite. Taken with plain light, magnification about 30 diameters. Taken to show the structure and make-up of this wery unusual specimen. 1 The principal constituent is olivine 2 The flaky shreds are antigorite 3 The black spots are magnetite — Plate 22 Photomicrograph of no. 77. A hornblende-plagioclase-gneiss (probably Grenville invaded by Pochuck diorite). Taken with plain light, magnification about 30 diameters. Showing: a Pyroxene with strong green hornblende border (dark grains with cleavage). b Plagioclase feldspar field (light gray). c Biotite (smaller flakes and dark smooth mineral). d Magnetite (black granules). e Apatite (high relief small light crystais). Plate 23 Photomicrograph of no. 55. MHornblende-plagioclase-gneiss (Pochuck). Taken with crossed nicols, magnification about 30 diameters. Showing: a Abundant hornblende (dark and rough). 6 Abundant plagioclase (banded). c A little quartz (clear grains). d A little biotite (dark flakes). Plate 24 Pochuck injection product. Taken with crossed nicols, magnification about 30 diameters. Showing: a Abundant plagioclase (banded) b Abundant hornblende (coarse dark) c Several large grains of titanite (very rough) } d A very little magnetite I Photomicrograph of no. 306. Hornblende-plagioclase-gneiss, essentially | Photomicrograph of no. 373-a. Magnetite schist (Grenville). Taken with plain light, magnified about 30 diameters. Taken in this light to show mineral association and structure. a Magnetite (dead black). 6b Pyroxene (dark and rough). c Quartz and feldspar (clear). d Apatite (white stronger relief). Plate 26 si Photomicrograph of no. 373-a-x. Maznetite-schist. Taken with crossed nicols, magnification about 30 diameters. This field shows the structure and mineral make-up of this rock. a Quartz (clear and with strain shadows). 6 Striated feldspars (a few grains). c Magnetite (dead black grains). d Pyroxene (rough grains). Plate 27 Photomicrograph of no. 432-a. Taken with crossed nicols, magnification about 25 diameters. Showing the microstructure in this specimen. A single original quartz unit covers a large portion of the field. It includes other matters among which are grains of feldspar, separate quartz grains, biotite and black gran- iles and the principal quartz unit is itself much strained and preserves evi- dence of fracturing and rehealing. Although the hand specimen has all the usual megascopic appearance of a quartzite, it is rather plain from a microscopic examination that the material is not of such simple origin. The quartz has all the habit of vein quartz, and its tendency to include other grains and be intergrown with other units of the same quartz make one believe that it is a differentiation extreme of mav- matic origin, similar to the quartz stringers described and illustrated in~ nos. 163 and 380. The feldspar grains and some of the other grains included in the quartz of this specimen have the same habit as have the original rock materials noted _in no. 163 and are believed to be remnants or representatives of remnants of the original rock which was invaded ‘by this quartz. GEOLOGY OF THE WEST POINT QUADRANGLE, NEW YORK 59 Although the rock shows abundant deformation effects especially fracturing and rehealing, it is evident that the composition as well as the distribution of minerals favors the theory of development from a fusion or solution. It may very well be that it is not a simple injection effect and this is indeed suggested by the presence of garnet in rather prominent development (plate 28). The occurrence of areas of quartz acting essentially as a host in poikilitic structural habit with the other constituents adds also to the certainty that it is not at all a metamorphosed quartzite in origin, but it is believed that there are remains of an older rock and that some of the minerals in it, such as garnet, are essentially syntectic products (plate 29). d Injection gneisses. The writers interpret many of the mixed banded gneisses as injection effects. In the coarser and more sharply defined occurrences there is no considerable doubt about this being their origin, but in the fine structured varieties where the different parts are not so well defined it is believed to be quite impossible to distinguish material of different sources. It is certain, however, that injection on a fine scale is quite as important in the gneisses of the Highlands as the coarse types, and this fine injection process doubtless gives much of the variety to the more obscure gneisses. If the injection habit is maintained distinctly in these five types one ought to see it occasionally in the microscope. As a matter of fact it is sometimes found very sharply defined on a microscopic scale. No. 163 has furnished several good photomicro- graphs for illustration (plates 30, 31 and 32). e Impregnation gneiss. A more intimate mixture than the type just described may be called an impregnation gneiss. Typically it pught to contain grains belonging to the original rock intimately associated with grains of introduced origin connected with magmatic ‘invasion. Although the conclusion is fully justified that such rocks pccur in considerable abundanee in this district, the finding of suitable illustration material is difficult and in even the best occurrences it is doubtful whether one could with certainty distinguish between the two sets of components. It has seemed to us in the examination of this field that the Canada Hill type of granite succeeds better in accomplishing such impregnation than any other type although the Reservoir granite is a close second and the dioritic magma, repre- sented by the hornblende plagioclase gneiss or Pochuck, has intimate penetrative habit also. One specimen taken from the Grenville gneiss belt in proximity to the typical Canada Hill granite shows sets of constituents that are believed to represent these two different 60 NEW YORK STATE MUSEUM sources. In this case the original is judged to be a representative off the Grenville series and the invading material is judged to be the Canada Hill granite. (Photomicrograph of no. 395 shows a typical | field.) The invading magma is represented chiefly by microcline and — the original rock material by the other more irregularly disturbed © and confused looking grains. The older minerals have multitudes of © inclusions and modification products whereas the invading minerals — are perfectly fresh (plate 33). Metamorphics of doubtful age. Three formations are classified — under this head in preference to connecting them more definitely in the historical sequence. They form a series including: (a) the © Manhattan schist, (b) Inwood limestone, (c) Lowerre quartzite. The first two are largely developed in this quadrangle and the last one very erratically or not at all. These formations can be traced from New York City, which is the type locality, northward to the Highlands into the southeast quarter of this quadrangle. Here they have a typical petrographic development, but their prominence in the field is much obscured by the heavy drift cover. The Cortlandt series also cuts into the area which would otherwise be occupied by these formations and eliminates about 20 square miles. No rocks of this type are found west of or northwest of Peek- — skill and the abrupt termination of so great a series with no rem- nants of similar habit beyond this border is one of the striking facts, and introduces one of the largest unsolved structural prob- lems of the region. It has been suggested that this series is the equivalent of the Hudson River-Wappinger-Poughquag series, but the authors feel that this has not been proved. In the lack of a better classification of age relations and, because particularly of the very strikingly different petrographic habit of these formations as compared with the other series they prefer to treat them in a separate class and are willing to consider their age doubtful. a Manhattan schist. The Manhattan formation is everywhere a schist of very complete recrystallization. In structural make-up it is strongly foliated and of dominantly micaceous composition. In some cases it is almost wholly mica with a light pearly mica predominating, but it varies from this to a strongly quartzose rock, essentially a quartz-mica-schist and in some of these cases black mica is fairly prominent. Pearly mica, however, is the most characteristic single mineral. At occasional points strongly hornblendic schists are developed from former igneous intrusions of essentially diabasic composition, but these are not largely developed in exposures of this quadrangle. a ——- fo. Plate 28 Photomicrograph of no. 432-b. Taken with plain light, magnification about 25 diameters. Taken for the purpose of showing a typical distribution of feldspathic and other material with the quartz of this specimen. Minerals present are: a Garnet, two large rough irregular grains. b Orthoclase, slightly altered (gray smooth). c Biotite, three or four small flakes at one side of the field (smooth dark flakes). d A crystal of zircon (rough) associated with the biotite. e A few black metallic grains (dead black). The rest of the field is quartz which is believed to be the youngest constituent and forms the principal mass of the whole specimen. The other rather isolated grains are believed to be remnants of a previously existing rock which has been invaded and replaced and largely absorbed. Plate 29 Photomicrograph of no. 432-c. Taken with crossed nicols, magnification about 25 diameters. This is the same field as 432-6, taken for the purpose of showing the structural relations, especially the complex interlocking of the quartz. FPhotomicrograph of no. 163-a. Taken with plain light, magnification about 25 diameters. Taken particularly to show the intimate penetration of injection matters, especially quartz. _dThe grayish portion of the field is chiefly made up of slightly altered feldspar and associated ‘quartz. These are cut by later quartz which appears in clear bands which, if followed farther in the slide, can be seen to widen or narrow and sometimes pinch out entirely as they extend into the solder material. Plate 31 Photomicrograph of no. 163-b. Taken with plain light, magnification about 25 diameters. A second photomicrograph taken from the same slide as no. 163-a. The field shows a similar habit to 163-a in that the older rock material is represented by the grayish bands and the newly introduced quartz by the clear colorless bands. _ ; : The older rock material is represented by slightly altered orthoclase and microline, by a little quartz in small grains, and by pseudomorphs made up of secondary chloritic aggregates. Some of these, no doubt, represent former ferro-magnesian minerals and are very dark. T he subsequently injected matter is quartz which cuts through and into the older material in tongue-like Stringers and narrow bands. Three of these are distinctly represented in this field, the central and widest one terminating within the bounds of this particular field. One of the others is a very narrow and somewhat broken looking stringer and at the opposite side of the field a third band wedges out to almost nothing. Plate 32 Another photomicrograph of no. 163. Taken with crossed nicols, magnification about 25 diameters. This method shows better the mineral habit of the rock with its coarse injection quartz and its much finer feldspathic original content. Plate 33. Photomicrograph of no. 395. Grenville gneiss. Taken with crossed nicols, magnification about 45 diameters. } Taken to show the mixed nature of a typical gneiss. This one is judged to be an injection or | impregnation gneiss in which the microcline can be clearly seen to cut or penetrate the other feldspathic constituents. The microcline has a stringerlike distribution in this field and is perfectly iI fresh, whereas the immediately adjacent orthoclase feldspar is much affected by sericitic alteration . 1] The constituents are in part of Canada Hill type and in part are judged to be of Grenville source . | GEOLOGY OF THE WEST POINT QUADRANGLE, NEW YORK 61 In places also pegmatitic injection effects are very prominent indeed and the rock is charged more or less with feldspathic and quartzose matters of this origin, so that it is much more complex in composi- tion at these places than is normal for the simple metamorphosed rock. More rarely other minerals are prominent, such as sillimanite, graphite, carbonate, sulphide, feldspar, tourmaline and garnet, but these are not by any means uniform and some are comparatively rare. The most widely distributed of this lot of constituents probably is garnet, which seems to be a regional metamorphic in origin. It is very generally and abundantly distributed in this formation. The rock is always foliated and sometimes streaked, but never banded. It is in many places crumpled in a very complex way, but this is not a universal effect. It is more likely to be streaked in connection with pegmatitic development and it is very seldom indeed that one can find any evidence whatever of original bedding, although the general structural trend and the limestone contact as well as certain sill-like meta diabases (hornblende schist bands) give some general idea of the formational attitude. The average microscopic appearance is illustrated by photomicro- graphs (plates 34, 35 and 36). Analysis of Manhattan Schist Composite of five specimens from the borders of the Cortlandi series, representing the different types. One is chiefly garnet, quartz and mica; the others carry considerable feldspar, along with the quartz and mica. SiO, 57-94 Mode Recast Al,O3 21.70 Otz. 19.20 ~ Fe:Os 1.57 Or. 5.56 FeO 5.90 Ab. 14.07 MgO 2.49 An. ue oC es Ite CaO .50 Muscov. 38.01 Na:O 1.74 Biot. 14.86 K:0O 4.68 Met. .70 H.O+ 2.17 Ilmen. 1.85 H.20— -29 P.O; tr 97. 35 ‘TiO. 1.01 MnO .19 100.18 Analysis and recast by G. Sherburn Rogers. 62 NEW YORK STATE MUSEUM The distribution of the K,O and H,O is entirely arbitrary. No account is taken of the garnet in this recast. b Inwood limestone. The Inwood limestone outcrops in a belt about five miles long, striking approximately East-West, in the south- east part of the quadrangle in Yorktown. The best exposures are ~at Amawalk and at the cross roads east of Mohansic lake. The lime- stone is comparatively nonresistant to weathering so that outcrops are few and inconspicuous. Open valleys tend to develop on this formation. It is a white limestone stained yellowish near the surface. The fresh fracture glistens with shiny mica scales. It is of medium coarseness with rounded or equant grains and crumbles readily in the hand to a rather coarse sand. In thin section it is a coarse-grained limestone carrying muscovite or phlogopite and a little tremolite. The calcite grains are rather simple in form, not well interlocked. They show the effect of dynamic stress in the twinning bands and the well-defined cleavage cracks. The mica is a later development. There is no good evidence here of contact metamorphism. The Cambro-Ordovician sediments. ‘Tiwo patches of Cambro- Ordivician sediments are represented on this map; one on the north margin of the Highlands at the foot of Breakneck ridge where a part of the lowland of the great valley comes within the boundaries of _ this sheet; the other place’ is along Peekskill Hollow creek. The types of sediments are represented by quartzites, limestones, shales, slates, phyllites and graywackes, belonging to three distinct forma- tions as follows: a Poughquag quartzite. This rock is developed in beds approxi- mating 600 feet in thickness. It is in general an almost pure quart- zite. It has been completely indurated and to some degree recrystal- lized. Certain beds have an appreciable feldspathic content and others have a carbonate intermixture in considerable amount. It has enough iron also to give it a little color so that chemically it is not quite such pure silica as the appearance of the rock would at first lead one to believe. There are no unusual petrographic features or characteristics introducing special questions or uncertainties of interpretation. b The Wappinger limestone. This formation is represented by a finely crystalline limestone. The beds lie immediately above the Poughquag in conformable relation and are developed to a thickness of approximately tooo feet. In no place in this district, however, is the thickness determinable, except as an interpretation from the Plate 34 Photomicrograph of no. 499. Manhattan schist. Taken with plain light, magnification about 25 diameters. : Showing: a Foliate structure. 6 Quartz (clear grains) abundant. c Biotite (dark smooth flakes). d Fibrolite (fibers and needles). e Pyrite (black large grains). # Garnet (rough gray grains). g Magnetite (small black specks). Plate 35 Photomicrograph of no. 1. A typical specimen of Manhattan schist. Taken with plain light’ Magnification about 30 diameters. ; ; Showing: a Strong schistose structure. 6 Mineral make-up including (1) quartz (clear grains), (2) muscovite (clear plates), (3) biotite (dark plates), (4) garnet (coarse rough crystals), (5) iron oxide, a little (black specks). Plate 36 Photomicrograph of no. 492-b. An injected or impregnated variety of Manhattan schist. Taken with crossed nicols, magnification about 25 diam- eters. Showing very irregularly distributed constituents including: a Abundant ‘biotite (foliated) b Abundant plagioclase feldspar (banded grains) ce Quartz (clear grains) d Fibrolite (rods) e A very little magnetite GEOLOGY OF THE WEST POINT QUADRANGLE, NEW YORK 63 folds in Peekskill Hollow. The rock is not so coarsely crystallized as the Inwood and older limestones, but is recrystallized sufficiently to destroy traces of such organic remains as may have been present. As a result, no evidence from that source is available from this material. There are no special peculiarities. The rock is quite granular where it is affected by decay or leaching, such, for example, as was encountered in the borings of Peekskill hollow, but on exposed surfaces deformation effects such as crushing and rehealing are brought out prominently by differential weather- ing. The bedding, except in very badly deformed zones, is distinct and easily followed, and as far as observed, there is no contact meta- morphism produced in this type. c Hudson River formation. The Hudson River formation is very variable in quality of beds represented. Some of them are very fine grained and were originally muds or silts, which by regional meta- morphism have developed into slates and phyllites. There are no undisturbed beds either of this or any of the other formations and on this account simple shales are not to be found at all. Some of the beds were originally lithic sandstones which have become quartzites and graywackes and shaly sandstones. The pet- rographic variety is as great as the whole range of such mixtures could be. The principal types are represented by the following: (1) A graywacke. This is a greenish rock of granular habit having all the general appearance of the so-called bluestones of the Catskills. This is not the formation, however, to which the true bluestones belong, although it has furnished similar structural material for local use. The chief interest attaches to petrographic habit and composition which show that the rock is made up largely of fragments of rock ‘instead of mineral fragments. Many varieties of rock are represented in these constituent grains, the commonest being fragments of rock of types not very unlike some of the beds of the Hudson River formation itself; that is, slaty and gritty and granular rocks of moderately metamorphosed condition. Fragments of dolomite are sometimes seen also and of course simple grains as well. The fact that the formation is made up largely of matters that represent older formations of very much the same type, formations which must have been metamorphosed at the time that the Hudson River formation was being accumulated, is very significant. It is in this respect similar to the true bluestones of the Catskills which are made up chiefly of lithic grains believed to represent in that case derivation from the Hudson River formation and its asso- 64 NEW YORK STATE MUSEUM ciates, which were at that time exposed to erosion by folding and uplift. It is an interesting fact, therefore, that the Hudson River forma- tion shows similar derivation from something which preceded it. Rock like the Hudson River graywacke could not have been made from such a series as the Pre-cambrian basement on which it now rests, represented by the gneisses and granites of the Highlands. It could, of course, have been made from the simpler metamorphosed sediments such as might be assumed to represent portions: of Gren- ville or portions of the Manhattan-Inwood series. This is a case, therefore, in which petrographic interpretation of the character of the material constituting a rock has a decided bearing on its possible relation to other formations in the region. ; (2) Phyllites and slates. The simpler slates require no further attention in this discussion. The most modified of the Hudson River formation representatives in this district are the phyllites of Peekskill hollow. This rock is recrystallized, sheared, somewhat crumpled, and perhaps granulated also in certain parts. It has minute mica flakes abundantly developed which give the phyllitic habit to the rock. As a matter of fact, however, quartz is much more abundant in the rock than the hand specimen would suggest and it has essentially a quartz-mica composition. In no place, however, is it coarse grained. This is of particular significance in view of _ the fact that the Manhattan schist formation with which this phyllite is sometimes correlated and which occurs at Peekskill only about a mile distant is very strongly foliated and very coarsely and com- pletely recrystallized. The phyllite carries many pyrite crystals or pseudomorphs after pyrite and occasional black carbonaceous looking material but other identifiable constituents are rare (see accompanying photomicro- eraphs of this type, plates 37, 38, 39 and 4o). The Younger Igneous Rocks Peekskill granite. The Peekskill granite is a small irregular- shaped mass about 3 miles long and 2 miles wide with its longer axis running N of E, lying east of Peekskill. It is well exposed in two quarries, one on the Crompond Road about 4 miles east of Peekskill and the other a little east of the road running south from Mohegan lake. The latter occurrence is the site of a quarry. The product is known in the trade as Mohegan granite. It has an igneous contact with the gneisses and schists, cutting them irregularly and sending pegmatites out into them. None of its ‘Rals ey lat Ve Photomicrograph of no. 47. Annsville phyllite. Taken with crossed nicols, magnification about 25 diameters. Taken to show one of the more granular varieties of this phyllite. Note a The numerous large quartz grains b The general phyllitic habit of the rest of the field The important constituents are quartz and mica. Other matters are of small consequence. Plate 38 Photomicrograph of no. 158. Annsville phyllite. Taken with crossed nicols, magnification about 25 diameters. This specimen shows the typical phyllitic structure and the composition which is almost wholly quartz granules and mica flakes. Photomicrograph of no. 24. Annsville phyllite. Taken with crossed nicols, magnification about 25 diameters. s mote Showing the typical structural quality of this rock and its principal make-up. The chief features are: a Very bunched distribution of granular aggregate quartz (clear). 6 Very minute flaky mica giving a streaked structure. c Presence of considerable carbonate. Plate 40 Photomicrograph of no. 24-2. Annsville phyllite. Taken with crossed nicols, magnification about 30 diameters. A different field in the same thin section. Showing the nature of the spotted varieties of this rock. a Quartz (clear) showing tendency to granulation of large grain. 6b Mica (large shreds). c¢ Carbonate (rough grains). _ GEOLOGY OF THE WEST POINT QUADRANGLE, NEW YORK 65 a ndaries is faulted. It has no physiographic expression, as in the ° hlands all rocks have so nearly the same hardness that physio- hic features are usually the result of faulting and physical con- n rather than of original petrographic quality. The rock is a light gray, medium to coarse-grained, acid granite composed of quartz, white feldspar, striated and nonstriated, mus- covite and biotite. The mica is not abundant and shows no signs of orientation. _ In thin section it is a coarse-grained rock of granitoid structure. The essential minerals are quartz, microcline, albite, orthorclase and scovite, with accessory.biotite and epidote. The quartz and micro- line were the last minerals to form and the microcline contains ores of the other feldspars. The epidote is a primary mineral and s intergrown with the biotite and muscovite. The rock is fresh xcept for slight kaolinization of the albite and bleaching of the tite, and it shows no signs of dynamic stress beyond an occasional ained quartz grain or bent mica plate. Analysis 6847 Granite—Cornell"dam (Peekskill granite) Norm. Or. JNO || AWE |) (Se Met. | Hyp. Q. 2 ae 73.54 1225 144 480 OOM Se al acai 8 533 ; 15.20 149 24} 80 30 RS eat sie ly ohana Ie eae .50 3 : sagt ied | Mousa lite, BO as ae ene .81 De Fass eal 23. Sea | ANA eat 3 OM Eh aa 2 a .03 Op aes cibsieoN Nd UL lla antl sald ek Bead on ae 1.69 |. BOM Pre cence lea re ROM Vero imege trae cas el tereos tes OM Rceen ean 4.99 - SOU mae er CSO) [ok et Pam Tues bl (PPR eG eR eye Ut ees ae. 2.31 24 DW Race ad URE eg che age me (he eee MMI real PPR se 533 x 6c = 31.98 WE 24" x 556 — 13.34 Mists 3) x 222 ——' = 270 r| Ab. 80 x 524 — 41.92 Hyp. 8 x 132 = 1.06 {Ab 278 8.34 Corundum 15 x 102 — 1.53 Femic... t 76 SI vy ast Sal. 7 >— =I Persalane Fem. £ Q 825i 13 = aeenek = ee a Brittanaire F * 7 Nab+K0 104. 7 ee ee — — Toscanase — CaO 30 Llu 66 NEW YORK STATE MUSEUM K:0 24 ain 1 —=— —= — — >— = Lassenose Na,O 80 5 Mode OE oe 32.94 Biotite OT re cian Bee: TG a 3H.O. Fes03.4 SiOs ADs ete a eee 41.92 4 KO yeh AlsO3 nS SiO» Aaa ngth: UREA Ee 8.34 8 FeO 4 SiOs Se ee ae 43 Tleminite...... 15 BiOt eee 3.02 Plagioclase = Ab, An; = Oligoclase Extra AlO.... Poss : Analysis and recast by G. Sherburne Rogers Analysis 6945 Mohegan granite Norm. Or. Ab. | An. | Cor. | Met: | Hypaii@s 16) Quartz == 30. 48 M Magnetite .70 Orth. —— 21 568 P. Hypersthene 2.15 F Albite == 36.16 Anorthite = 66.67 Femic 2.85 Cc Corundum = 1.53 Salic 96.52 Sal 96 i —=— = >-=I Persalane Fem e I Q 30.5 aaa ; : — = —— or < - >-=4 Brittanaine F 64.6 uy NasO+K;0 108 vpn ass ee = oe On a eceaiiace CaO 24 Too8 K:30 39 Se —=—or <-— >-=4. Lassenase Naz,O 69 Sed) Lassenose (symbol 1.4.2.4) Near Toscanose Analysis and recast by G. Sherburne Rogers. Cortlandt series. The geology of the Cortlandt series has been worked out in considerable detail by G. S. Rogers.7® ** Geology of the Cortlandt Series and Its Emery Deposits. Rogers, G. Sherburne, Annals, N. Y. Acad. Sci., v. 21. I9mI. GEOLOGY OF THE WEST POINT QUADRANGLE, NEW YORK 67 a 3 _ The following abstract from Roger’s paper gives the main results of his investigation. | b The Cortlandt series of-basic, igneous rocks lies in Cortlandt town- ship south of Peekskill. It covers an area of 25 to 30 square miles. ‘Smaller outcrops of similar rock have been found in New Jersey and at two places in western Connecticut. Stony Point on the wes: side of the Hudson is made up also of these rocks. The series cuts the Cambrian limestones, but not the Triassic sandstones at Stony Point. It is therefore Postcambrian and pre- ‘Triassic and from the absence of metamorphism the author concludes that it is post-Ordovician, but pre-Permian. Tihe main mass of the rocks is norite, but “examples of nearly every group from pegmatite to peridotite have been found with local developments of very peculiar and abnormal rocks.” The basic rocks are difficult to distinguish in the field as they are all dark pink or gray. The rock types described in detail are syenite, sodalite syenite, diorite, gabbro, norite, biotite-norite, biotite-augite- norite, quartz-norite, augite-norite, hornblende-norite, biotite-horn- blende-norite, olive-augite-norite, hornblendite, pryoxenite, horn- blende-pyroxenite, olivine-pyroxenite, peridotite, and the dike rocks, aplite, pegmatite, dacite porphyry, dioritic and gabbroic dikes, horn- blendite and serpentine (peridotite). Six of these rocks are of importance areally and are described below. Diorite. The diorites grade from pure mica-bearing to pure horn- blende-bearing rocks. The brown hornblende-diorites grade into the norites, the green hornblende-diorites into the biotite-diorites. They are generally of medium grain, but with abrupt changes of texture although not of composition. Orthoclase is often present with the plagioclase, which may be oligoclase to andesine. The hornblende is usually in poorly defined grains of green color with inclusions of ilmenite. Occasional primary quartz and epidote are found. Apatite and garnet are occasionally abundant. Strain effects are found occasionally in wavy extinction of quartz, granulated feldspar and bent biotite. Biotite-norite, biotite-augite norite, and hornblende-norite. Biotite- augite-norite is the most important of the norites. It is medium grained and dark pink or dark gray. It seldom shows meta- morphism. The plagioclase is usually andesine which obtains its pink color from a fine hematitic dust, but may be labradorite in the darker rocks. Orthoclase may be present up to one-third the amount of feldspar. Hypersthene, biotite and green augite are the 5 68 NEW YORK STATE MUSEUM other essential minerals. Apatite, ilmenite, pyrite and pyrrhotite occur as accessories. This rock with decrease of augite becomes the biotite-norite, and with occurrence of brown hornblende and decrease of biotite and augite becomes the hornblende norite. Hyper- sthene is the chief constituent of all the norites. It occurs in stout, ‘rounded prisms of different degrees of pleochroism. Oriented ilmenite inclusions are common. The alteration is usually to ser- pentine, but occasionally uralite forms. Olivine-pyroxenite. This rock is made of augite or hypersthene with varying amount of olivine. When the percentage of olivine is large, the rock disintegrates easily into a coarse red sand. The topography of this region shows numerous rounded hillocks. The proportions of pyroxenes vary; almost pure olivine-augite and olivine-hypersthene rocks are known and basaltic hornblende is a fairly constant component. The olivine makes up usually one- fifth to one-third of the rock. It is colorless, but contains magnetite inclusions. It is nearly always somewhat altered to serpentine. The contact rocks have been described in detail by Williams.” Staurolite, sillimanite, cyanite, and garnet, biotite and magnetite are typical of the contact with the Manhattan schist. At the limestone contact are pale green amphibole and pyroxene with rarer titanite, zoisite and scapolite. Inclusions of schist, limestone and gneiss in the igneous rock are common. The inclusions show more or less effect of absorption by the igneous magma. The series as a whole shows little evidence of dynamic meta- morphism except around the borders of inclusions, but there is a banded gneissoid structure which is believed to be original and proof of magmatic differentiation. “It appears that we have a fairly complete and very intimate complex. . . . In some places the complexity of the mass is bewildering, while again we may have several miles of a fairly uniform rock. . . . An infinite number of species might be differentiated within this small area of 25 miles” (p. 57). “ The various differentiations of the norite magma are most centrally located; they are flanked on both sides by pyroxenites and between the norites and the western area of pyroxenites lies a diorite area. * “The most basic members at least shade into one another in many cases, while at times sharp contacts may be found. The analyses of the more important types indicate an unmistakable ™ Amer. Jour. Sci. (3), 36:254. 1888. GEOLOGY OF THE WEST POINT QUADRANGLE, NEW YORK 69 serial relationship. It is probable that the latter (the pyroxenites) were intruded first, followed closely by the norites so that sometimes these varieties are found banded together in flowlike masses. The diorites must have come next.” STRUCTURAL: GEOLOGY (Larger structural features) The larger structural features represented in the district are of enough variety and complexity of origin to warrant discussion under a separate head. ‘These features may be grouped as follows: 1 Internal structures of formations, especially those with igneous control or history. 2 Form represented by the individual units shown on the map. 3 Tectonic features or deformation structures. 4 Metamorphic structures. Internal Structure Detail ' The larger units belonging to the Precambrian all show a variety of structural detail, the chief of which is a streakedness grading into clear-cut banding on one side and into massive habit on the other. This has already been referred to in its genetic bearing in connection with petrogenesis. It is sufficient in this present con- nection to emphasize the prominence of this feature, which charac- terizes practically all the older units. It is a structure which is of particular prominence in those belts where the Grenville sediments are more or less in evidence, but is not by any means confined to the Grenville limits. As already pointed out, the origin of much of the structure is due to an actual mixing of types, so that a grada- tional boundary rather than a sharp line division ought to be expected and is commonly found. In spite of this fact, there are reasonably clearly defined large field units, and their internal structural detail, however complicated, must be considered of minor significance. In addition to the streakedness and the banding already noted, there is xenolithic structure representing incorporated blocks of older material as one extreme and also pegmatites representing final stages of crystallization as the other. These two habits add further to the irregularities and structural variety of formations. The total result is the apparent structural confusion referred to in an earlier chapter. As a matter of fact, these differences are not abnormal to | 70 NEW YORK STATE MUSEUM the formations in which they are found if one takes their history into account. They do give, however, the impression of hopeless confusion and a certain vagueness of character which adds much to the difficulty of satisfactory field determination. Not only is the identification of a formation obscured by this variability, but its boundaries are to a large degree uncertain and the identity and inter- pretation of a given occurrence are frequently difficult or impossible. Certain structural characteristics may be credited to syntexis or absorption. One of these is a gneissoid structure where the original country rock itself had pronounced structure and especially if it was made up of differing streaks or bands (plate 41). A result much less uniform than the gneissoid habit is derived from the incorporation of massive material, and this does not develop gneissoid structure without accompanying magmatic move- ments. The more common effect in such case is a patchy habit of the invading rock not caused by simple differentiation. With mag- matic movement it is believed that syntectic portions of the magma may develop striking structural qualities, simulating even the definite banding of an injection gneiss. . The injection type of structure, however, is usually much sharper, and, in the ideal case, has determinable differences of material in the alternating bands. In the typical case, injection may not involve much absorption of the invaded walls or much syntexis, and it ought to be possible to distinguish rather sharply the character of the injection material, connecting it directly with its true source. Asa matter of fact, there are all gradations between complete syntexis and clear-cut simple injection, and the commoner occurrences are intermediate in behavior. They have certainly accomplished a good deal of modification of the invaded rock, and have evidently worked over portions of the walls and to some degree invaded the weak- nesses of these walls, so that everywhere the invasion matters are intimately intergrown with or mixed with the original rock material. It is perfectly clear in great numbers of outcrops that an injection process has given the fine strikingly banded structures characterizing them. The clearer cases are those in which some transverse cutting of the formation occurs in addition to the banding which usually follows accurately the original structure. This cross-cutting of the structure is always taken as proof of invasion origin, whereas simple banding in the absence of such supplementary evidence has at least other possibilities. Similar structural habit may possibly be derived by differentiation + ‘YOO1 OY} JO. UOVOYTpIOS [VU VOUS J1OS stip} JO UONBULIOFOP OU Udoq Sey a10Y J, “TOWIUTeY oY} 4e puULG Pe}NeF IY} OJON “JUOLWOAOLU BUIdVLE [PUSIVLU JO j[MSor ay} Ayorys Ayqeqord st ynq ‘yo0r ysOY OY} SE YSIYA “ystyos URWeYURPY, EY} WoOTF siNjON1S Pojtoyur Ue yied ur oq ABUL SIU, ‘[[LEYSyoed eau so}soU sotios jpuelJIOD oy} Jo suorjsod [euLs1ewW UE PoAtosoid oInjontjs Plossteus spn.) Iv 93e[g 3 GEOLOGY OF THE WEST POINT QUADRANGLE, NEW YORK Ty under movement, as suggested by many writers on such phenomena, but this is not so clear. It is certain, however, that differentiation has some structural possibilities, and this is clearest with the pegmatitic facies. Nowhere in the Highlands does there seem to be such a thing as a segregation mass, such as a marginal ore, but that separa- tions of this kind probably did take place is indicated by the occur- rence of magnetite bands of pegmatitic habit which appear to have been injected. The features referred to in the foregoing paragraphs make up what has been referred to elsewhere as the structural confusion of these older formations. Other features than those mentioned may be encountered but they are all believed to be of the same general genetic meaning. Forms Represented by the Individual Units In the series of formations mapped, some are sedimentary beds and have a distribution characteristic of such beds modified by the deformations which are included in their subsequent history. The Hudson River-Wappinger-Poughquag series, the Manhattan- Inwood-Lowerre series and Grenville formation were primarily sedimentary. Except in the case of the Hudson River-Wappinger- Poughquag series the original structural habit is much obscured by subsequent metamorphic and igneous history. This obscurity is developed to an extreme in the Grenville where a large part of the original bedding is completely destroyed and only the secondary structural habit is preserved. Enough remains, however, to prove that bedding was a fundamental structure in this oldest formation of the region. _ The igneous formations occur in a variety of structures, some of which are bosses and perhaps others are laccolithic or sill-like. The behavior of the Canada Hill granite suggests bathylithic rela- tions. Nearly all the igneous masses conform more or less to the trend of the region and the primary control of this trend is undoubt- edly the structure of the Grenville. All the larger masses have such relation and form, but a far greater variety of form is represented by smaller units, too small in fact to be mapped. These are the injection bands and stringers as well as dikes and veins which cut through the earlier rock constituting the inclosing walls. The most clearly marked units of this kind are dikes, but their promi- nence and importance are insignificant compared to the abundance of the pegmatite bunches and stringers, the veins and the injection bands. 72 NEW YORK STATE MUSEUM It is probably impossible to determine the structural relations of the successive igneous invasions. It is difficult to conceive of the method of approach which might give one of the later magmas opportunity to invade superior rocks in so many places, especially thoroughly crystalline and substantial rocks. That this happened, however, is certain and a magma reservoir of very wide distribution must be assumed. All these necessary assumptions are strengthened by the conclusion reached in the discussion of correlation, which indicates essentially identical igneous formations, and probably actual connection between similar units, occurring in the Adirondacks on the one side and in the Highlands of New Jersey on the other. There is no doubt about the petrographic similarity of these types and the only logical conclusion which seems to be warranted is that certain of these magmatic masses must have had a remarkably widely dis- tributed plutonic development. The simplest conception would seem to be a great bathylithic mass extending beneath the whole region thus invaded which by its successive manifestations of igneous activity produced the separa- rate individual units of the series of this area. It may indeed be that the different units are nothing else than successive developments from this single larger plutonic source and that the historical range represented does not transcend the limits of its long magmatic history. In this case, products furnished by the distinguishable field units must represent simply the manifestations of particular periods of magmatic activity. It is difficult otherwise to conceive of conditions which would produce so widely distributed results of similar character with all of this peculiar complexity of structural relation. A plutonic mass capable of producing the first effects. if allowed to crystallize completely, could not, on subsequent igneous invasion, yield the complex structures found so abundantly dis- tributed in this territory. It would seem, therefore, that the funda- mental conception, as the source of all the older igneous masses, is that a single great regional bathylith, in its successive periods of activity, has produced all these results as steps in a single but long continued magmatic history. Deformation Structures These structures include unconformities, faults, folds and crumples, crush zones, slaty cleavage, shear products, streaked habit and schistosity. Some of these are of large geological significance, such as the unconformities, folds and faults. Some of the other | ‘l 7 GEOLOGY OF THE WEST POINT QUADRANGLE, NEW YORK 73 _ features depending largely on dynamic influence are simply different _ expressions of metamorphic history. Unconformities. Pre-cambrian unconformity. Only one well- , marked unconformity has been demonstrated in this area. ‘This is _ the unconformity between the gneisses of the Highlands and the Cambro-Ordovician series of sediments. In a few places it is clearly shown that the whole complex structural habit exhibited by the gneisses was developed and exposed to erosion before the Poughquag quartzite was laid down. ‘The form of surface is much modified by subsequent deformation, but the condition found at the best occur- rences indicates a comparatively smooth cleanly swept erosion sur- face so that the first layers of quartzite are in contact with fresh, unweathered gneiss. The quartzite is simple and comparatively pure right from the start and this condition requires not only that erosion should take place under such conditions that the bedrock of that time could be completely denuded, but there must have been unusually perfect assorting and selective concentration to produce such a rock immediately on a granite floor. The finding of trilobite fragments in certain beds of the Pough- quag quartzite shows beyond question that this formation was devel- oped in the sea margin, but it is a striking thing that it has no conglomeratic habit and practically no arkosic composition. It is difficult to see how it would be possible to make such a formation directly from the disintegration of the gneisses. One would expect a history involving the destruction of earlier sandstones of less purity which themselves might have been derived directly from the gneisses. Perhaps there has been such a history, but there is no evidence of it at this point beyond the fact of the purity of the quartzite and the lack of conglomeratic facies. If the Manhattan- Inwood-Lowerre series, however, is, as we now think, older than the Poughquag, it may be that the destruction of members of that series furnished the material of the Poughquag. If that source is not the right one it is difficult to avoid the belief that some other Cambrian or Precambrian formation now entirely missing in this region was destroyed in the making of the Poughquag. In any case the Cambrian unconformity is a very profound one and undoubtedly marks a great geologic hiatus. The actual unconformity can best be seen near the north margin of the quadrangle where, in a few places, the quartzite still lies only slightly tilted on the old erosion surface, while the adjacent outcrops of gneiss show their usual steep inclination. No actual observation FA NEW YORK STATE MUSEUM has yet shown igneous transgression of the Cambrian unconformity in this area although it is possible that this does not hold farther to the south and to the east. It certainly does not hold to the south if the Manhattan-Inwood series is Cambro-Ordovician, but reasons for questioning that correlation are given elsewhere in this paper. One of the latest of the great igneous invasions belonging to the Pre- cambrian series is the Storm King granite which is, we believe, the equivalent of the syenite series of the Adirondacks, and it is most prominently developed in the very section where the unconformity is best preserved. Whatever igneous activity there may be of Post- cambrian age must be much later than this. Even the dikes which cut the Storm King granite do not cut the Cambro-Ordovician series. It is our belief that only the Cortlandt series fulfils this last condition. It appears, therefore, that the Cambrian unconformity is here a complete break separating both the ancient metamorphics and the whole great series of igneous intrusives from the later Cambro- Ordovician sediments. When one appreciates that these intrusives are large, deep-seated masses of very massive habit and could not possibly have developed near the surface, this unconformity takes on some‘hing of its true significance. It represents an erosion inter- val of vast time during which some thousands of feet of overlying rock must have been removed. The same unconformity has been found on the west side of Peek- skill creek west of Putnam Valley and the relation is the same, except that the erosion surface has been tilted until it stands verti- cally. But satisfactory exposures are difficult to find. On the east side of the valley, although both the quartzite and underlying granite are well exposed, the structural relation is obscure because the under- lying member is a rather featureless granite instead of a true gneiss. It is very significant, however, on this point, since the granite here is the so-called Reservoir granite. It is clear that the granite does not cut or in any way affect the adjacent quartzite. Here also the quartzite member runs so straight and true in spite of the fact that it is tilted into almost vertical position that one is impressed with the evident uniformity and monotony of the erosion surface on which it was formed. The similarity in thickness of the quartzite as developed in this valley and on the northern border seems to argue for the same thing. A great deal of attention has been given to the question of a pos- sible additional unconformity in this southeastern Ney; York region. ‘ ; j GEOLOGY OF THE WEST POINT QUADRANGLE, NEW YORK 75 It has been quite natural to look for it at the base of the Manhattan- Inwood-Lowerre series and sometimes an overlap has been postulated to care for some of the descrepancies. Thus far, however, no obser- vations can be said to establish fully another unconformity or even a definite overlap. As a matter of fact very little evidence on that point can be gathered from this particular quadrangle because the Manhattan-Inwood series is too much obscured by drift cover to furnish reliable data. Pre-Triassic unconformity. Another great unconformity sep- arates the Triassic from ali the earlier series, but the structure itself does not figure in this quadrangle since the sediments do not cross its southern margin. It was the erosion work of that interval, how- ever, which stripped some of the Cambro-Ordovician sediments from the region, as may be seen by examination of the basal conglomerates of that age just to the south. It appears, therefore, that the Pre- Triassic erosion interval is a factor of some prominence in a full his- torical statement although it is not possible in this quadrangle to point out the actual unconformity. Post-Cretaceous unconformity. The next erosion surface which served at one time as an unconformity was the Cretaceous peneplane which is still to some degree preserved. After it was partly dis- sected Tertiary deposits must have been laid down on it over this area and still farther inland. These were all stripped from it in preglacial time and the old unconformity (the Cretaceous peneplane) subjected to additional erosion. The result is a somewhat more com- plex surface forming the preglacial floor than would be possible from a single erosion epoch. Glacial unconformity. The last unconformity is that between the rock floor of glacial time and the glacial drift itself. Faults. The region is one of many faults representing several different ages. It is doubtless impossible to determine the age of some of these faults and it is also impossible to locate all of them. The fairest statement that can be made on that point is that they are much more numerous than any inspection of the ground will dis- cover and doubtless many of the most ancient ones are completely obscured by rehealing, injection and complete recrystallization. Thus it happens that most of and perhaps all such structures of Grenville age are lost. It is probable that very few Precambrian faults can be detected with any certainty although evidence of rehealed crush zones may be detected with the microscope. In one of the tunnels of the Catskill aqueduct, however, a typical 76 NEW YORK STATE MUSEUM fault breccia was encountered so perfectly rehealed that the rock is completely crystalline and does not develop weakness on weather- ing. A second fault of similar behavior developed a very fine shear zone which crosses the northwest corner of Iona island and strikes northeast across the west flank of Anthony’s Nose. It is so sub- stantial that the rock within the zone, which is essentially an epidote schist, is as resistant as the adjacent unmodified ground. Other similar shear zones have been noted elsewhere and beautiful shear schists of most remarkable structural habit have been obtained from them (see petrographic section), but there is no topographic expres- sion to emphasize the occurrence of the faults of this type and unless one just happens upon them they are overlooked. They all fall, however, into the lines of general structural trend and undoubtedly they belong to some period of Precambrian deformation. (See plate 42 for illustration of the microscopic features of this material. ) All Cambrian and later faults are probably so imperfectly healed in this region that their occurrence is more readily detected. Although there may be several series, it is doubtful whether more _than three can be well established — those belonging to the period of the Taconic folding, those of Appalachian mountain making and those belonging to the Triassic period. Even this much is more than can be differentiated very accurately. 'The first two are especi- ally confused and perhaps in some cases there has been movement along the same line in more than one period. It is possible, however, to locate definitely a number of faults which are of large displacement. The Highlands belt itself is an up-thrust block with fault boundaries to the north and south. The fault lines run obliquely to the general trend of the belt itself instead of exactly parallel to it, and it thus happens that cross-faults give an irregular saw-tooth effect to the boundary. Although several have been definitely placed on the map and others are drawn tenta- tively on the basis of structural weaknesses or radical change in formation, it is certain that many more faults actually occur, and that the district is much more complicated than is shown by the accom- panying map. The faults of largest determinable displacement are the one at the north margin of the Highlands along Breakneck mountain, and the one which extends from Tompkins cove northeastward along the west margin of the fault block of Peekskill valley. In both cases the displacement must be more than 2000 feet to cut out the formations a prare Plate 42 Photomicrograph of no. 74. Grenville schist. Taken with plain light, magnification about 30 diameters. Taken particularly to show the minor structural features of a shear zone schist of Grenville age. Composition chiefly epidote, quartz, feldspar, sericite and titanite. The very streaked structure and augen structure are well developed, but this particular specimen shows in addition, micro-faulting and tendency to rhombohedral fracture. It is noticeable that the quartz is abundant only in lighter bands and is either introduced or reorganized quartz, in either case essentially introduced at this spot, whereas in some other occurrences of different date the shear- zone material seems to be simply crushed and redistributed materials which belong to the rock without any additions from without. It is posstble that this difference in content gives a clue to the age relation. In other words, it is probable that this is a very ancient shear zone of Post-Grenville Pre- cambrian age whose deformation is connected with the healing influences of invading granite. In this case it is probably of Canada Hill age. GEOLOGY OF THE WEST POINT QUADRANGLE, NEW YORK Le actually missing at the fault line. The Breakneck fault is a great thrust, causing the gneisses and granite of Storm King and Break- neck ridge to ride up on the Hudson River slates. The Tompkins Cove-Peekskill Valley fault is connected with a down-dropped block and must have a different structural relation and movement. Since | these two are characteristic of the faulting of the region they deserve a special descriptive note. The Storm King-Breakneck fault. This fault is readily traced by the abrupt change in formations in the northwest corner of the quadrangle, but the ground is badly covered in most of this area and the actual condition is very much obscured. Immediately to the southwest, however, just beyond the margin of the quadrangle on the north side of Storm King mountain the fault is well exposed and very definitely located both on the surface and several hundred feet beneath in the Catskill aqueduct tunnel (Moodna tunnel). The fault plane is simple, and is traceable in fairly definite form for a considerable distance. It dips at not far from 45 degrees to the southeast. _ The rock in the hanging wall is the Storm King granite and gneiss, chiefly the mixed types that are called gneisses, rather than the Storm King granite proper. The foot wall is at some places Hudson River slate and at other places Wappinger limestone. In the vicinity of the Catski!l aqueduct line, the surface shows slates and the tunnel level 300 feet lower shows limestone. In both cases the adjacent rock is crushed on an immense scale, especially on the foot wall side. For 200 feet the limestone cut by the aqueduct tun- nel in the foot wall is crushed and rehealed to such degree that it is absolutely impossible to determine the bedding of the rock. Its ‘exact attitude therefore is entirely unknown. In addition, blocks of slate are dragged into the principal fault zone and some of the gneisses are so crushed and altered as very nearly to resemble the slate. It is perfectly clear that this is a thrust fault, that the Highlands gneisses and granite have been pushed over the bordering quartzite- limestone-slate series and that the movement has been sufficient to cut out all the quartzite and at most points all the limestone. Prob- ably such patches of limestone as are found are dragged into place by the fault movement. Since the quartzite is rather continuously about 600 feet in thickness in this district and the limestone is more 78 NEW YORK STATE MUSEUM than a thousand feet, it appears that a movement of at least 2000 feet is determinable at this point. The displacement on the average, doubtless amounts to more than this. The fault zone for the most part is not healed except in the lime- stone. There is no very satisfactory way of determining the age of this fault because nothing later than Cambro-Ordovician is involved. A considerable development of formations as high as Devonian, however, lies just a little farther to the west, and their position is such as to prove that this faulting was subsequent to their deposition. It therefore can not be earlier than the Appalachian deformation and may be later than that. Considering, however, that the Triassic and later types of faulting are more prominently simple block faulting, this fault, which is a strikingly strong thrust type, must belong to the Appalachian deformation epoch. No doubt there are many other similar lines in the Highlands that date to the same period. It is possible indeed that some of those on the south side of the Highlands are of this age and may have suffered additional movement in later time. On account of the con- fusion of the geological formations within the Highlands the amount of displacement is seldom determinable. There is no object in undertaking a detailed description of each fault. They are numer- ous and of various degrees of prominence. The Tompkins Cove-Peekskill Valley fault line. The fault which enters the quadrangle from the southeast at Tompkins cove forms, farther south, the division line between the sandstones of the Triassic lowland and the gneisses of the Highlands. It disappears, however, as the principal line a few miles to the south and its place is taken by a parallel fault of like habit lying to the northwest of it. This forms the boundary between the gneisses and the Triassic sediments for many miles in the Ramapo quadrangle of northern New Jersey. This fault displacement brings phyllites of essentially similar qual- ity to those of Peekskill valley in contact with the granitic gneisses of the Highlands. The same thing is true along the west side of Peekskill valley where phyllites of Hudson River age are brought in direct contact with the granite of Cat Hill and adjacent territory. It appears in this case, again, that 600 feet of quartzite and 1000 feet of limestone are cut out, together with a considerable amount of phyl- lite, so that doubtless again 2000 feet displacement is not too much to reckon. But in this case the depressed member is on the southeast side and the raised member is on the northwest, just the reverse of that at Storm King-Breakneck, and this result could not be obtained by a thrust movement. GEOLOGY OF THE WEST POINT QUADRANGLE, NEW YORK 79 In Peekskill valley the formations are very distinct, and the whole Hudson River-Wappinger-Poughquag series is fully represented. It is clear that a tilted and down-dropped block forms the whole floor of this valley, the formation standing practically vertical on the - _ east side, the principal fault movement being recorded on the west side. Exploratory work has been carried on in connection with the Catskill aqueduct investigation which gives accurate data on the location and attitude of the rocks across the whole valley, even where they are heavily covered with drift. The major structure, therefore, ‘is very well known and the main facts on those explorations may be found in N. Y. State Mus.. Bul. 146. The striking thing in this isolated block of Cambro-Ordovician sediments is the close isoclinal folding which seems to have tripled the thickness of the limestones, while the block shows down-faulting of a sort that is difficult to associate with the type of folding repre- sented. It seems necessary, therefore, to invoke the aid of deforma- tion of two periods, first a close folding of the Appalachian type which probably took place in Appalachian time. Second, a down- faulting and tilting of the block which belongs to the period of Trias- sic deformation. The chief deformation zones of these two periods are nearly parallel and this causes confusion as to which period really caused the folding. Also it is possible that some folding and shear- ing accompanied the block faulting. It does not seem reasonable, however, considering the simplicity of the typical Triassic blocks to charge much of the folding of this isolated block to the deforma- tion of Triassic time. It is entirely possible that block faulting preceded the Triassic period of deposition also and thus outlined some of the principal areas of that formation. The great Triassic block which carries many thousands of feet of sediments on the west side of the Hudson in northern New Jersey and adjacent portions of New York, would be such a case. At the extreme northeast point of this acute-angled block the unique igneous intrusive masses known as the Cortlandt series are located. ‘This intrusion seems to have followed the weak- ness developed at this angle where several faults converge. It is not possible to say how many dislocations belong to the Trias- sic deformation. Undoubtedly there are some examples in the Highlands and also north of the Highlands, but nothing of equal prominence to this Peekskill Hollow fault presents data of decisive enough character to warrant description. Possible other types. The sudden ending of the series of crystal- 8o NEW YORK STATE MUSEUM line schists and limestones represented by the Manhattan-Inwood formations, and their attitude at the boundary with the gneiss in the southeast quarter of this quadrangle suggest a sharp flexure along the margin which may have the same meaning as a fault line. It is a question whether that boundary might not better be represented as .a fault. It is not clear, even so, whether it would represent any different age relation from those already discussed. The reason for calling attention to it is the suspicion that this particular deformation may date to a much older period than either of the two just described, and this may account for the sudden disappearance of the Manhattan-Inwood series farther north. It is, in other words, connected with the very confusing problem of the interpretation of the Manhattan-Inwood series. Minor structures. In addition to the faults of a major sort, there is an endless variety of crumples, minor faults, drag effects, etc. which are the incidental accompaniment of major deformation. In some cases they are undoubtedly simply secondary and tertiary and minor drag effects. In other cases a similar appearance is. created by movements in the magmatic masses, where partially digested slabs of older rocks are distorted or where poorly distributed matters are drawn out and twisted by magmatic movements. These give great variety of appearance to the formations under discussion, but they do not deserve detailed treatment here. Folds. One’s first experience with the Highlands gneiss struc- tural features, especially the high angle of dip which nearly all formations of the district have, leads one to assume a very profound folding as one of the contributary causes. Undoubtedly much fold- ing has taken place and such structural features as belong to folds are especially well developed in the Cambro-Ordovician and in the Manhattan-Inwood series. But it does not appear, after further consideration, that much of the structural detail of the gneisses or of the banded and streaked rocks of mixed origin have been greatly influenced by folding, except such as may date back to Grenville time. It is clear, from knowledge of the structural history of the gen- eral region to which this area belongs, that it must have been within reach of the deforming forces of every mountain-making period since Grenville time; but it may very well be that deformation in the form of folding has not affected these massive members of the Highlands belt as much as the more superficial and less competent overlying sediments. It must be appreciated that the Highlands belt ‘YJNOS IY} JO S}SIYIS dy} OF OPIS YYAOU oY} JO SoPZ[S OY} WOIY SOSSlOUD PUL SoyUvIS JO }o4 SPUL[YSIF] O41Uo oY} SUISSO1D MOLI ‘9 “SMU [e1oueS B UL UMeIG ‘de I130[008 oy] UO Y-Y eUl] oY SuUOle ofsuLIpEND JurOd ISOM Of} FO WOHIOS SSOTy IISO[Od") agizang henbybroy pus auaqsatl 7 dabulddoy, aqizziond bonbybroy Say-1afl Pub S271401Q Saze/s 4aAly uospny fo 291UP19 /j/} PPOUoD Ul paphyaii/pue Kqpag2a/%! pic eucgsaui7 Jabulddoy, Jo $3443 pplbjp409 BPU0LD WY SYIAL 20/9 pagjNbf{ -uMoq Sau0zsalu/] pub sassiaub ‘ szsiy2s {0 Sal/aS d/)hua49 agiuD49 buisy 4045 S290/C 42Al\/ UOSph}y Tae 1 = y Avg! Ji Hh Ayastematit ; & 00s aglUD40) HOA SASL x oo goa! x Squbuuay ayiAliar9 fo Jag /PLIDUl4d v 6 > 00S} Oost Qq >» ¥ g ~ S Yd N Ly) a) RS ies Loe} Ra 8 Qe S Q Qos & 13 4 RG ny 3 NaN x x Nae 8 Ny RN oO Aiea Ss & 8 8 2 v8 > $ 3 30 os es x ae 5 q ¥9 : = in g 4 Sy x S ay $ > ui § ¢ nv Saas 3 ~s & h > x > oy x > 2 2 g + aes % NS + 4 oF Ss €v 23eId GEOLOGY OF THE WEST POINT QUADRANGLE, NEW YORK 81 has been thrust up to a much higher relative position with respect to the bordering country, both north and south, in comparatively recent geologic time. Part of the uplift certainly dates from the Triassic, since which time there has been no folding in the region. It is the writers’ belief that the Grenville structural habit and attitude and distribution indicates folding of that formation dating back to very ancient Precambrian time. There is no claim that distinct repetition of beds can be detected, but the very definite northeast-southwest trend and the marked control over all igneous intrusions resulting in a similar orientation of them indicate that this formation, which is the oldest of the region, must have had this structure before the igneous history began. The only way by which a series of sedimentary strata can exhibit a regional trend is by deformation and we regard this regional habit therefore as satis- factory proof of the folding of the ancient Grenville. If the Manhattan-Inwood-Lowerre is also Grenville, as we are now inclined to believe, much of its folding must also be Pre- cambrian. . The Post-Ordovician or Taconic folding must have affected the region also and later the Permian or Appalachian folding was imposed upon it. Thus it happens that the Cambro-Ordovician sediments to the north and the down-faulted block in Peekskill valley, and the schists and limestones of the southeast quarter are all much deformed by folding, but to which of these periods the chief deformation should be credited is a matter of much obscurity. It may even happen in the case of the down-faulted block in Peekskill valley that its fold- ing is in part connected with the Triassic faulting. On the whole, the chief folding belonging to the members on the south margin of the quadrangle is of comparatively ancient time, and that affecting the Cambro-Ordovician of the north margin belongs chiefly to the period of Appalachian folding. All the folds trend northeast-south- west except for minor flexures and local pitches and the deformation of every period seems to have had nearly the same orientation. Most of the folds are asymmetric and sometimes overturned toward the northwest, and the major structures are accompanied by all! the nor- mal minor folds and crumples of the second, third and fourth and still higher orders which might be expected in a region of such extensive deformation. 82 NEW YORK STATE MUSEUM ECONOMIC AND ENGINEERING GEOLOGY Mineral resources A region of such variety of rock type would lead one to expect that the mineral and structural material resources of the district might be very promising indeed. This is all the more expectable when one takes into account the complicated igneous and meta- morphic history which might readily have produced important mineralizing effects. It is somewhat surprising, therefore, to find that mineral resource development has been very limited. At numer- ous places quarries have been opened and rock for structural pur- poses has been produced. At a few places economic minerals, such as pyrite and iron ore, have been worked in former times. Sands and gravels have been produced as well as road metal, lime and clay. More recently, investigations have emphasized the presence of material for crushed rock, high-grade silica, water and other things. These will be taken up briefly. Building stone. Large amounts of stone suitable for structural use are available. The chief items are granite, quartzite, limestone, marble, and gneiss. Granite. A very excellent and unusually attractive granite has been quarried 2 or 3 miles east of Peekskill at two places, both in the younger granite formation, known in this paper as the Peeks- kill-Mohegan granite. A very light-colored, almost white granite was quarried in a portion of the area nearest to Peekskill usually known as the Peekskill granite quarry. This quarry furnished stone for the New Croton dam, and although it is very suitable for build- ing purposes and because of its fine color, would be a strong com- petitor in the New York City market, the quarry is not now worked. This is in large part because of troublesome jointing conditions. There is nothing against the quality of the stone and it is possible that at some other point work could be established where excessive jointing would not interfere. It is an interesting bit of history with regard to this quarry that suit was brought against the operators, who worked it for the supplies used in Croton dam, for ruining the quarry, the claim being made that the jointing condition now seen in it was largely pro- duced by extravagant and careless use of explosives in quarrying. Although it is true that the use to which the material was to be put, made it possible to utilize much rough broken rock and that on this account very careful handling was not so necessary as for GEOLOGY OF THE WEST POINT QUADRANGLE, NEW YORK 83 ‘regular structural stock, yet it is perfectly clear that the jointing which has caused the real trouble is natural. A mile further east across a stretch of low-covered ground, the Mohegan quarries lie in the same formation. Several openings have been worked at this point, most of them comparatively small. A - peculiar color quality is produced here which makes the stone unusu- ally attractive to architects. The Mohegan granite has been used in the Cathedral of St John the Divine of New York City. The principal color is a sort of buff, which is very unusual for a granite, but it seems to be strictly a primary color. Both of these quarries are marginal in the granite mass which is _ genetically related to the Cortlandt series. No other places have been worked in this rock. A granite quarry was opened some years ago on the south side of Breakneck mountain and a considerable volume of stone was removed. It was abandoned, however, apparently because of the close jointing and the structural irregularity of the stone. This rock is the Storm King granite type which has a rough gneissoid habit and strong pegmatitic tendency. Both of these tend to make the quarrying of massive blocks difficult. These characteristics do not necessarily interfere with use for rougher purposes than build- ing stone, such as crushed stone or cyclopean masonry or for foun- dations; but it is doubtless the difficulty of working, especially the tendency to produce irregular and curved surfaces in quarrying, rather than its petrographic quality that has discouraged working. At many other places small workings may be seen, but most of them have figured only in local use and are so placed that the trans- portation handicap could not be overcome for a wider market. High-grade granites from other sources meet the requirements of the market so fully that it would require extraordinary conditions or particular quality to gain a position of economic importance. It is true, however, that granitic rocks both of massive and especi- ally of gneissoid varieties occur in very great abundance in this quadrangle and could be produced in large quantity. Their quality is good enough to meet all normal requirements, but considering all controlling factors it is not likely that large supplies will be drawn from any of this ground for building stone purposes. An occasional gneissoid type of rock is found to give rather good architectural effect and it may possibly be that such quality of rock will be in higher favor in the future. If such a thing should 6 84 NEW YORK STATE MUSEUM happen it would be difficult to find a more promising field of develop- ment than the gneissoid granites of the Highlands of New York. Limestone and marble. A very high-grade, finely crystalline limestone occurs at Tompkins cove, following the margin of the down-faulted block at that point, and extends from the river south- westward to the limit of the quadrangle. The beds stand at a high angle and are associated with a phyllite in similar manner to the association of these two rocks along Peekskill creek. They are judged, therefore, to belong to the Hudson River-Wappinger series and the Tompkins Cove limestone is accordingly correlated with the Wappinger. Beds vary greatly in quality, some of them being highly siliceous and certain beds more strongly magnesian than others. The density of the stone, however, and its large development, together with its excellent location for cheap transportation as well as other favorable conditions at this locality have made the working of this stone a very large and prosperous undertaking. The stone is as good quality as can be produced from limestone. It is used very extensively for ordinary crushed stone purposes and the market in New York and vicinity, where it supplements the trap rock and other crushed stone demands for various structural purposes, absorbs the total production. The rock is rather strongly metamorphosed and has developed silicates to some degree from its original impurities, but this trans- formation has not made it coarse and granular and weak to the degree attained by some of the other limestones, notably the Inwood. The following analyses represent the chemical quality of the stone: 1 Analysis recorded in New York State Museum, 51st Annual Report, 2:450 (1897); also in Bul. 44, p. 438 (1911): SIO’ Sos d idan seach ne cencgeaee Mere soea thes ee ect ee Olt elena ate ee 12.00 PATO: Gisin Lae wikis oko in ENGL btw ahi blogic Cubsahin 2} se gaibite MUR PG la tres Sin ieee che ean 4.13 OAD ES wcrc ace oizinttie HORDE delesle G snaie sin eneawalte Otic so cette 1.05 CaGOw? . 20 f ET aT EY ene 2 | a 23.34 MS GOR hits. os CARI OUISRIS Ble GREE LL cds, FASTER A tale «ee 16.74 GO che yey! Silo cin = tare t sp dmtapapyenetg pierece's ejaiere'sctye 4 bp > Rela 39.1 2 Analysis made by Richard K. Meade, Baltimore, Md. (1919); furnished by Calvin Tompkins of the Tompkins Cove Stone Co.: Sade aays i oi RAY Bits iailc aie wie aud aleys fe Ryle OO els Siotete, Chak iit ken Sco ee 8.10 Tron oxide ‘and Altimnay 5.5.6. pels ck tie ale fete ase be Oe 1.24 Carbs ot Meine. oP a. LR SITE SS, Pe Ee 54.50 GarbylMapnesias:. ge. 22. ..dee ie bo Wiick Stele ale GOneee Gee ee ee 36.36 eS Ce GEOLOGY OF THE WEST POINT QUADRANGLE, NEW YORK 85 3 Analysis made by Edison Company (1908); furnished by Calvin Tomp- kins of the Tompkins Cove Stone Co.: aes TMNT CUMME eet ec ral ea iha Soa Ba cha el cals ato Gaus ina ayn 1 3 ag 54.00 De S Sel cays te iche cic cs jane ml a eyaholngs ag iye's «e/a p cle eres Sine alae s 36.00 (EE 3s qc ihiGLRMoei takai coreg CLG Garner Rinaihs nena p ai ir O¥oo: adem lnon wandy Ailimlina sale 20s ae die co eet PN 6 ONE TOL 4.00 4 Analysis made by A. A. Brennan, 97 Water st.. New York (1919) ;. fur- nished by Calvin Tompkins of the Tompkins ‘Cove Stone Co.: Two samples of limestone were determined for magnesium carbonate content MAMIE PAE INITLE bh 5 ldo wary ai'vich'slavese o xyainseeters sre.n's ave 27.67% Magnesium carbonate Miemere4 ((eravish White) os... 2-6 eee. see 4s 30.71% Magnesium carbonate A continuation of this same formation may be traced along Peeks- kill hollow for several miles, but it is everywhere covered rather heavily with drift and does not stand favorably for exploitation. This condition is somewhat better as one traces the beds to the northeast, but transportation becomes more difficult and the prospect of competing successfully with the other limestone quarries situated on the Hudson river is questionable. On the opposite side of the river from Tompkins cove, at Ver- planck point, there are other quarries also in limestone, which have been extensively worked. They are quite as favorably located as those at Tompkins cove, but have not been developed so system- atically and the character of the stone is somewhat different, in that metamorphism in the direction of strong, rather coarse recrystalli- zation is much more pronounced. This affects the quality of the stone to some degree, and it is therefore placed at a disadvantage since the fine-grained varieties are preferred. There is a large avail- able supply here, however, and certain beds are undoubtedly service- able. _ Crystalline limestone of Inwood type occurs in the southeast corner of the quadrangle between Yorktown Heights and Amawalk. The rock is a true marble in its crystalline habit and certain beds are quite as good as the Tuckahoe marble. The rock is, however, rather coarse and soon shows the effect of the weather. On this account the Inwood type of stone has little market. Although it would be possible to produce any quantity of this stone from this and adjacent areas farther to the south it is not likely that large development will be undertaken chiefly because of the short life of the stone. A quarry was at one time worked in the Sprout Brook limestone, which is an interbedded Grenville limestone. It is an exceedingly complexly metamorphosed rock with much deformation and igneous 86 NEW YORK STATE MUSEUM injection and development of silicates. The structure is very vari- able, the quality is quite erratic and the grain is prevailingly coarse. On account of these facts, the rock is not so serviceable as the others for the ordinary higher grade purposes. It was, in former. years, burned for lime and was used also in connection with local iron smelting ; but it has not keen worked now for many years. A very large development of this limestone is found in Sprout Brook valley, however, and any special quality belonging to this type could be produced on a large scale. Lime. In earlier days lime was produced from certain of the limestones in this area. At present no lime burning is practised although certain beds of the Inwood are used in this way at Ossin- ing, a few miles farther south. Undoubtedly similar quality of product can readily be made from the limestone of this quadrangle, but a high-grade quality to meet the competition in the market is not likely from any of these formations. Quartzite. A belt of quartzite approximately 600 feet thick extends along the east margin of Peekskill hollow for many miles. This is the Poughquag quartzite belonging to a down-faulted block. It stands almost exactly on edge and its southern exposure is in a hill at least 100 feet high, not far from the Hudson river. It is almost an ideal location for working, but nothing has been done beyond investigating the quality. It is a high-grade quartzite rock carrying only a very small percentage of impurities and has been examined on this account for its possibilities as a glass sand. These results have been reported by R. J. Colony in a recent bulletin of the New York State Museum'* in which the following analysis of a mixed sample is recorded: S10 AAs A te ee am ieee tne Ee ea by tS! MER SOM pilates 05.51% BECO g PE aloe RE VAR he SS Ts OREO SO 0.27% PIONS cid bu.0e ens Sugiase side loarh we eidtnda we Oe ade que aleianpes cneeeee nr 2.3570 MA a itis seth Sides oowe aapyd "An + & mlbydin os eumawiebaaiel gle etal AAs un olbes alee eae 0.07% PURE irate Sis 3 (> poy ials o'sycuahy «© 0:5) aah tetBinn ce wie catet nreuiateieets eval ata ae 0.390% Mr Colony notes that not all the silica in this rock is quartz, how- ever, that feldspar grains are numerous and no doubt these grains are the chief source of the alumina. : Similar or even better quality is to be found on the north margin of the quadrangle where the Poughquag is exposed. None of these occurrences, however, is so well situated as that at Peekski!l creek for cheap transportation and unless a very high-grade quality *N. Y. State Mus. Bul. 203-4, p. 22 (1919) ; also p. 8-9. : j { GEOLOGY OF THE WEST POINT QUADRANGLE, NEW YORK 87 could be discovered in those beds it is not likely that any of them would be worked for the present. A very small outcrop of quartzite has been noted east of Peeks- kill along the east margin of the Peekskill granite area, but its extent is undetermined and its quality is unknown. If a high-grade quartzite could be shown to have a quality for structural purposes not fully met by the siliceous limestone and _ trap and other rocks, which supply stone in such immense quantities and under such favorable conditions along the Hudson river, it might be that the quartzites of this quadrangle would ultimately become the foundation of a large industry. The question has received attention recently, but thus far no development has been undertaken. Iron. A good many years ago iron was produced from this quadrangle at several points and a furnace was located at the mouth of Peekskill creek. A narrow gauge railway connected this plant with the producing properties, but this, together with the plant and the workings, have been abandoned for so many years that only obscure ruins remain. Iron was brought from! the belt of iron- bearing rocks which follows the west side of Sprout Brook valley and extends almost exactly through the center of the quadrangle in a long belt running northeast-southwest. The ore is magnetite and has pegmatitic associations and probably igneous origin. The bodies proved to be rather small and the mineral considerably mixed with silicates. Doubtless large quantities still remain and it is possible that modern treatment of some of these deposits would be found practicable. Occasional occurrences of similar sort lie out- side of this belt already referred to, but nothing of consequence has been noted of any different relation or origin. Pyrite. At a point somewhat east of the summit of the moun- tainous mass known as Anthony’s Nose, was formerly located a mine producing sulphide of iron, the product of which was used in an acid plant near the present Highlands station on the New York Central Railroad. This plant was in operation up to about 15 years ago, but has been abandoned in recent years. Its total supply was not obtained from this mine, however, and finally the mine was not depended upon at all. What the actual condition is at the old mine can not be deter- mined because of danger of entering the workings. It is clear, however, from inspection of the occurrences at the surface and from the material on the dump that the ore was associated with pegma- 838 NEW YORK STATE MUSEUM tite much like that of the magnetite deposits. In fact magnetite also occurs in this deposit. Remarkably large crystals of the constituent minerals are developed here, including immense slabs of hornblende and masses of pyroxene. This agrees well with the assumption of igneous origin connected with pegmatitic development. No other deposit of similar nature seems to have been worked at any time. Pyrite, however, is not at all rare in the Grenville and to a small extent in some of the other formations, but none is known with high enough content to be considered workable. The quality of material at the Anthony’s Nose property was said to be poor because of the presence of pyrrhotite in addition to many intermixed silicates. Sand. The glacial deposits, a large amount of which is modified drift, contain numerous occurrences of washed material and fairly well-sorted material answering the purposes of stuctural sand. No very high-grade deposit, however, has been examined, but certain occurrences situated in proximity to engineering undertakings, where such material was needed, have been extensively used. One of these is known as the Horton sand deposit at the north end of the Garrison tunnel a short distance east of Garrison. The deposit occurs in a typical kame formation, is very variable in quality and of comparatively limited usefulness although it has considerable local extent and was extensively used in the building of the Catskill aqueduct. Other similar occurrences may be found and some are used for small local supplies, but there is nothing of extraordinary value except perhaps a gravel deposit on Jones point which has now been completely worked out. Gravel. At Jones point, on the Hudson, just opposite Peekskill, a rather remarkable deposit of coarse gravel has been worked for many years but is now practically exhausted. It 1s washed glacial material of the heavier sort from which practically all the clay and finer material have been removed. The pebbles were largely hard crystalline types and on this account produced a very high-grade gravel for road metal use. This at one time was in great demand. Search has been made for similar deposits elsewhere to supplement the declining production from this place. Although gravel deposits are not rare, a high-grade pebble content is surprisingly rare and thus far none has been found to meet the requirements so well as that at Jones point. Most deposits have too much sandstone, shale and limestone and too little crystalline rock content. Road metal. Crushed stone for structural purposes, including Joo} OOF JOY JO UOIVAV[O UB Je [OUUN} UOSLIIer) JO puUd YOU oY} JV SE SIL Jonpenbe [[Pysjey oyy Aq JNO Sl JI 19M PUNOIS UOJIOFF 24} UO UOsiIIer) JO jseo s}isodop omey, oY} UI }flIp poyIpoyy x a Zz a CS a ee GEOLOGY OF THE WEST POINT QUADRANGLE, NEW YORK 89 road metal, is produced at Tompkins cove in very large amount. It has also been produced at Verplanck point and in former times some production was furnished from the Iona Island gneiss and from the Storm King granite at Storm King mountain. None of these is now active except the Tompkins cove plant. Possibilities of producing any quantity of granite gneisses and similar rock are very good indeed, but it does not appear that the quality of material produced for this purpose from such sources can compete with the stone already in the market from the trap formations and the siliceous limestones. It is possible that some of the quartzites may furnish a particular quality, but these have not been tried out and as far as known, they do not promise a quality superior to the trap in any case. As long, therefore, as trap supplies are obtained at a moderate price, it is not likely that any of these possible sources will be used extensively. They undoubtedly will be used locally for many purposes and especially for road building. This quadrangle, in short, contains its own structural material for all sorts of building and construction purposes but does not promise any considerable supply to the stone market. Clay. Clays are developed along the Hudson river in considerable quantity, but the workable deposits are chiefly beyond the limits of this quadrangle. -The large Haverstraw brick plants lie just south of this quadrangle and others of similar sort occur to the north. One at Dutchess Junction in the northwest corner of the quad- rangle is worked on a large scale. Smaller amounts occur on Verplanck point on the south. The origin of these is the same as the well-known Hudson River clays connected with the close of the glacial period. The quality is suitable for common brick manufac- ture. No large industry could be established, however, within the limits of the quadrangle except such development as the deposits near Dutchess Junction will afford. Water. The region has a rainfall of 48 inches and the streams from the mountainous and sparsely settled portion of the region furnish excellent water for all ordinary uses. Some of these are used locally as water supply for such places as Peekskill. Local supplies for farms or individual use are not difficult to secure in most districts by wells. No water of extraordinary quality is known within this region. An occurrence of rather surprising behavior, however, has been encountered on Foundry brook not far from Nelsonville above Cold Spring. Here a boring put down through the drift and into rock, go NEW YORK STATE MUSEUM for exploratory purposes in connection with the Catskill aqueduct investigations, encountered a water-bearing zone in the crushed gneisses or granites along a fault, and a flowing well was thus developed. This furnished the basis for an extra damage claim in connection with the condemnation proceedings and the nature of that claim is described in connection with engineering problems on a later page. The quality of the water is good but nothing extraor- dinary for such a region. Doubtless similar quality can be obtained elsewhere at numerous places, but it would not be easy to discover another combination of circumstances. which would be certain to produce a flowing well. | Emery. The Cortlandt area near Peekskill is one of the very few places in America from which emery is produced. These deposits occur in the norites of the Cortlandt series as rather limited local developments. They exhibit very unusual mineral association, among which are magnetite, corundum, spinel and epidote in addi- tion to or instead of the usual minerals of the norite series. These patches usually have a distinctly banded structure which is normally lacking in the norites themselves and which suggests the existence of some older rock which has been in large part destroyed, but whose structure is in part preserved. They probably represent xenolithic masses which have been able to attract from the magmas in which they were immersed or have at least helped to fix certain constituents which together with those already in the rock have given the abnormal minerals of the emery deposits. This origin was suggested by the senior author some years ago during his study of the Tarrytown quadrangle and the detail has been worked out in a petrographic study by G. S. Rogers,’® whose dis- sertation on the Cortlandt series furnishes the best description of this area. The following items bearing on the emery deposits them- selves have been extracted from his paper. Description of the form- ation is given in a different section. “ The abrasive, emery, is an intergrowth of magnetite and corun- dum. It occurs in veins and pockets with occasional well-developed lenses. The types are spinel emery, pure emery, feldspathic and quartz emery schist, associated with norite and sillimanite schist.” Rogers summarizes his description as follows: “1 The ore usually occurs in a region in which mica schist inclu- sions are abundant and often within a hundred feet or so of such an inclusion, and the largest (McCoy, Dalton etc.) are within 1000 feet of the border of the Cortlandt series. * Rogers, G. S., N- Y. Acad. Sci., Annals, 21:11-86 (1911). r vi t GEOLOGY OF THE WEST POINT QUADRANGLE, NEW YORK OI 2 The ore is always in sharply defined veins, pockets or lenses, but its constituents often occur disseminated through the rocks immedi- ately adjacent. 3 The ore is immediately associated with abnormal rocks, con- taining sillimanite, cordierite, garnet, quartz, or allanite, which are found nowhere else in the area, except around certain schist inclu- sions near Crugers; or more rarely it adjoins rocks which are normal except for the spinel scattered through them. There is often a great abundance of biotite around the ore, which is also characteristic of these inclusions. 4 These rocks often exhibit evidences of shearing, faulting or cracking, which is rare in other parts of the district, except around schist inclusions.” . The theory advanced to account for the occurrence is that the emery is formed by the absorption of the Manhattan schist in the basic magma of the Cortlandt series. The streakedness of the ore resembling the structure of a schist, and its occurrence near the con- tacts of the igneous rock and around schist inclusions, the presence of sillimanite, garnet and biotite, and the gradation from norite, through emery into schist, are the chief arguments for the theory advanced. Considerable amounts of material of this type are available from the district. It is not a high-grade product, however, and con- sidering the fact that the market is chiefly supplied by other types of abrasives and that a higher grade emery comes to the market from foreign sources there is no immediate prospect of more exten- sive development, although it is likely that small production will continue for an indefinite time. This is an interesting economic resource, although it is not one of large consequence. Its interest centers largely in the rarity of its mineralogy and in its origin. Ball mill pebbles. An interesting special use of the very hard and tough material forming the emery deposits has been tried out by Edres Herbert. He conceived the notion of using this material in ball mills for grinding purposes as substitute for flint pebbles. The foreign supply of flint was cut off by the war and-substitutes were in demand. Preliminary tests have shown unusually encourag- ing results and there seems to be promise of a limited use of this kind for this material. Its weight and toughness are two points in its favor. Graphite. The mineral graphite is not at all unusual in the Grenville rocks. It is found in considerable abundance in certain of 92 NEW YORK STATE MUSEUM these formations along the eastern side of the Hudson from Garrison southward, but no occurrence is known which would encourage exploitation. Most of these occurrences are undoubtedly of the same general origin as is usual in the complete metamorphism of sediments, and _this particular content probably is derived from original carbonace- ous materials which belonged to the rock. Flakes of graphite occur in the schists and gneisses and limestone members, but it is more apparent in the very schistose rocks than in the others. An occur- rence of this same type at Tuxedo, 20 miles farther west, was investi- gated with considerable care a few years ago by Mr Lorillard of Tuxedo, and there have been other attempts to determine the work- ability of this material; but thus far none has succeeded, and most investigators have gone no further than the preliminary stage. The prospects in this quadrangle are certainly no better than at many other points and there is no likelihood of them proving valuable for this mineral. A very interesting occurrence of the same mineral in entirely dif- ferent form is found near the west margin of the quadrangle west of Dunderberg. This is an occurrence of graphite in a pegmatite vein. The graphite occurs in large plates and is associated with mica and quartz and feldspar. It is not developed on a large enough scale for exploitation, but it represents a not uncommon type of occurrence. The graphite must in this case have an igneous history. Similar occurrences are found on the east side of the river northwest of Garrison. General summary of economic resources. On the whole, the economic resources of the quadrangle are not extraordinary in any respect. For a region of such complexity of geological structure and history they are rather strikingly insignificant. There are prac- tically no mines and the prospects of furnishing products of very high grade of any sort are, to say the least, only moderate. The only industries of this sort which may lay claim to rather unusual quality in the market are those connected with the Tompkins Cove limestone, the Peekskill granite, and the Peekskill emery. Engineering Undertakings The Highlands of the Hudson lie directly across one of the great- est lines of transportation of the United States. Such transporta- tion facilities as the Hudson river itself presents, raises no question at this point because the river is deep and wide enough to accommo- ——————— ~“yuL0d “SIt]} qe lo. \TT Foe fO Ip rut a} Ul s pue ‘Avmoyes sty} Ys SOI} 9 oy J Aeur ‘supyonyd me Aq pouedes}s uses aq -YSIF] 9y} 0} ABMo}eS YOU OY} BUTTUIOF JOOF OOTI IY} FO ZFeYS ayejJdn IO NOoUYeoIG oy} JOAO J9quIeYD 9}¥35 JY} ST PUNOISII10F 9Yy} Ul SutpPyInq ot], “ST SMOTICU SMI IL, ‘UTeJUnOUL Suly WIOJS fo det oy} Je JOAII UOSpnyT oy} Jopun ‘qOOIpPoIOE [JE1s3#D 94} JO Sutsso19 UOspNfT oy} FO osanod oy} Ut ods UMouy jsodaop oy] JO SurpMos9 ay} Aq pouedsopie! \O SBA JOS} 95108 Ssoq}qnop ‘IQATI OY} ssos0e AJ1oyJNoOs IY J, “Spury jouun} eimssoid Suly UITO}S FUL GEOLOGY OF THE WEST POINT QUADRANGLE, NEW YORK 93 date almost any type of vessel. In railroad building, however, the conditions are not so simpie. The sides of the gorge at many places reach the water’s edge in comparatively steep cliffs or rugged moun- tain sides and the upland is too rugged to encourage the location of any such transportation line. Two railways, however, follow the — Hudson river. The difficulties encountered by them are in part met by tunnelling and in part by filling and stabilizing the natural fill of the river gorge itself. No extraordinary problems have arisen in _this connection. A recent piece of engineering work, however, the Catskill aque- duct, has introduced several less common problems of sufficient com- plexity to warrant special note. Those of chief geologic interest are: (1) the Hudson river cross- ing at Storm King, (2) Bull Hil tunnel, (3) the Foundary brook crossing, (4) Garrison tunnel, (5) the Sprout brook section, (6) the Peekskill Hollow section. In a region of such complex structural habit and variety of relief, considerable difference in the practical problem is presented at these different localities. Thus it happens that in certain cases it is a matter of depth of preglacial channel; in others, a matter of quality of rock or depth of decay or source of structural material or water behavior. The cases selected for illustration are typical of problems belonging to engineering geology in a region of this kind. The Hudson river crossing from Storm King to Breakneck mountain. The Catskill aqueduct approaches the Hudson from the west at hydraulic grade, across the country back of Newburgh which is something over 400 feet above sea level. It is necessary either to keep this level by some sort of structure or maintain the pressure in some sort of conduit or pressure tunnel across the Hudson river to the east side, so that a 400-foot level may be maintained again across the Highlands. The engineers in charge of this work decided in favor of a pressure tunnel in bedrock as the most permanent and practical design for this undertaking, and the location chosen for the crossing was between Storm King and Breakneck mountain in the northeast corner of this quadrangle. . A careful study of other possible crossings was made by the senior author of this bulletin before this selection was made and it was finally determined on several accounts that this location had more known points in its favor and was more defensible geologically than any other. All the more favorable locations were in the Highlands within the bounds of this quadrangle, but several others outside of this area were also explored in some detail. 94 NEW YORK STATE MUSEUM The strongest point in favor of the Storm King crossing was the evidence that the tunnel beneath the Hudson would lie in a single type of rock, the Storm King granite, whose structure is more mas- sive and uniform than any of the others. . There seemed to be less danger also from faulting in that partie- ular spot than most other places along the Hudson river. The fault question indeed was one of the most vital in the problem. All but one other of the locations studied involved certainty of weakness within the Hudson river gorge itself. The quality of rock and the faulting problem were, therefore, the most decisive factors. ! A second-choice location was between Crows Nest and Stony Point and as conditions are now known there is no particular rea- son to disfavor such a crossing, as far as geological behavior is con- cerned. A third possible crossing, near West Point, involved a great crush and fault zone, which the river follows from West Point to Fort Montgomery. All the proposed crossings north of the Highlands involved tun- nels in the Hudson River-Wappinger-Poughquag series with a certainty of many faults and other structural difficulties and a very long stretch under pressure. No place superior to the Storm King location was available therefore on the most important counts. It was formerly assumed by many geologists and engineers that the Hudson river followed a fault line and that the gorge probably could not be crossed without encountering the troubles of the accompany- ing fault zone. Studies made at the time this problem was under- taken, however, indicated that most of the lines of the great fault system run diagonally northeast-southwest, crossing the river rather than following it, and that this is strictly true in the section between Storm King and West Point. Later explorations and observations made during the actual construction of the tunnel have fully sus- tained this conclusion so far as the Storm King-Breakneck locality is concerned. With regard to the other places, of course, no additional information is available. After choice of location, however, the chief controlling question was the depth of the preglacial channel. Before construction could begin and even before final estimates could be made, a particular depth for construction had to be determined upon, a matter of no easy solution. It was supposed by many engineers that the bottom of the Hudson had been determined at New York City as approximately 300 feet below sea level; but when this question was studied fully, it became ota & a ‘Juiod sty} Je TALI OY} SOSSOID YOTYM I}URIS SUI, WA0JG sy} FO JINjonIys poyurof AysR] “Novi pue A[Suo1s pue }IGeY VAISSEL OY} SUIMOTYS ‘TOATI OY} WOIf Usye} ‘UIeJUNOW sOoNY Yeo1g gv a3e[q GEOLOGY OF THE WEST POINT QUADRANGLE, NEW YORK 95 apparent that the actual bottom of the Hudson at its deepest point was not determined at all. It was also apparent that with the very deep gorge extending out to sea for 75 miles, measuring approxi- mately 4000 feet deep on the submerged margin of the continental shelf, a good opportunity was presented for a much deeper Hudson gorge in the district under study. It was soon found also that at no place along the Hudson between Albany and the sea was the depth fully determined. [Explorations therefore had to be undertaken. These involved exploratory borings in the river and, ultimately, inclined borings from shafts located on either side of the river. Irom outside sources of information and especially from wash borings put down in the vicinity of New Hamburg it was estimated that the depth to the rock bottom of the river would be more than 200 feet, but relying on the belief that the 300-foot depth reported at New York was reasonably correct, it was argued that the river gorge should not be any deeper than this and probably not so deep at the Storm King crossing. It was somewhat of a surprise, therefore, when one of the early borings in the river considerably to one side of the center, penetrated a great variety of materials, chiefly bouldery and gravelly drift, to a depth of 500 feet before striking rock. Great difficulty was encountered in putting down these test borings. Seldom has an exploratory investigation been undertaken under more discouraging conditions. Because of the tidal flow and river current, the machines had to be perched on platforms or fastened to the casings that were established as the first part of the boring opera- tion, while the power and other equipment was located on scows anchored beside them. The most difficult of all ground to penetrate is just such mixed structural materials as was found at this place. It is necessary in such case to start with a very large diameter casing, driving it as far as conditions will allow, and then, when halted by material which can not be further penetrated, introduce some form of churn drill or similar device which can be worked inside of the first casing tube. This permits additional progress through boulders or other obstruc- tions, but at the same time reduces the size cf the bore. As soon, therefore, as material is encountered which slumps, it is necessary to put down another protecting casing inside the first and proceed with it in the same manner as far as it will go. This is a time-con- suming and very expensive process and where very deep borings have to be made under such conditions, many additional difficulties serve to complicate the problem. For example, the Hudson is a 96 NEW YORK STATE MUSEUM great traffc-way. Great lines of canal boats pass in tow up and down the river. With current and tide these are difficult to manage, especially in attempted avoidance of these boring rigs placed adjacent to the main channel. As a result some of these boring rigs. were wrecked after long time and much money had been spent on them. ' The margins of the river, however, came ultimately to be very fu-ly explored, and the general form of the gorge was outiined to a depth of about 500 feet on each side. The central portion of the channel, however, for a width of something like 1500 feet was still unexplored, except by one boring which ultimately penetrated to a depth of 765 feet without reaching bedrock. Such results aroused much suspicion in the minds of the engineers responsible for this work and so much time had been consumed that uncertainties of this section were considered to be the most question- able feature of the whole aqueduct line between New York City and the Catskill mountains, endangering, in the minds of some, the success of the whole project. It was felt, therefore, that complete information must be obtained in some other way. Enough confidence was placed in the geological conclusions and evidence, however, to warrant continuation of the plans adopted and the construction already started at other points, to encourage expenditure on permanent work at this crossing. The plan adopted finally was to sink full-size working shafts on each side of the river so that they could ultimately be used for the finished tunnel. After sinking these to a depth of about 200 feet, rooms were cut in the solid rock and diamond drills were set up in them, one on each side of the river, at suitable angles to penetrate the ground underneath the middle of the river. The first trial was made at an angle which when projected reached a depth of 1400 feet at their intersection under the middle of the river. The geological results were satisfac- tory. Subsequently the drills were set up again at a flatter angle to intersect under the middle of the river at a depth of 950 feet. This also gave eminently satisfactory results, indicating the Storm King type of granite for the whole distance in both sets of borings. Surveys of the drill holes for deflection or deviation from the true angle indicated comparatively little correction and these two sets of borings were thereupon considered complete substantiation of the geologic conditions expected, as previously interpreted, and sufficient proof of the actual conditions to be encountered to warrant the immediate letting of contracts and the beginning of construction of the Hudson River pressure tunnel. Plate 47(a) Crow's Nest “Storm King Mt. Diagrammatic cross section of the Hudson river at the Storm King crossing, looking south, showing the completed aqueduct tunnel, the exploratory borings made in the river and the inclined diamond drill holes made from the two working shafts Plate 47(b) A diamond drill set up in a room cut out of granite work in the shaft at Storm King Crossing, at a depth of over 200 feet, drilling the inclined holes to explore the ground beneath the river GEOLOGY OF THE WEST POINT QUADRANGLE, NEW YORK 97 It is still uncertain, however, just what depth the preglacial gorge has. The boring from the river surface had reached only 765 feet and the borings from the side shafts had tested solid rock at 950 feet. The old channel bottom therefore lies somewhere between, but at - just what point there is no possibility of knowing. Assuming, therefore, that there might not be much of a thickness of rock above the 950 foot point reached by the shallower oblique borings, the engineers in charge of the project decided to locate the tunnel at a depth of 1100 feet so that there would be more than 250 feet of solid rock above the roof of the tunnel. This is the way it was constructed. Two dangers were faced in constructing a tunnel of this kind, first, that crevices or broken ground would be encountered, furnishing extraordinary amounts of water, which might interfere seriously with construction; second, that in operation the bursting pressure from the water flowing inside might rupture the tunnel and establish objectionable leakage. There was possibility also of encountering ground difficult to grout and seal against leakage, if not kept within properly protected formations. As a matter of fact, the fear of heavy inflow of water was a very live one, and extra precautions were taken in that direction, a considerable plant being established for pumping purposes. No serious difficulties, however, were encountered in this direction except temporarily when a water-bear- ing seam was cut, which flooded the east shaft beyond the capacity of the pumps then’ in operation. Later, additions to the pumping equipment were made on a large scale as a guard against emergencies but no further difficulties were encountered. The tunnel is finished with a solid concrete lining inside the granite walls averaging nearly 2 feet thick, and the joints in the rock back of it are filled with grout which was forced into them under pressure. The inside surface in contact with the water is smooth and the finished tunnel is 16 feet in diameter. The aqueduct waters thus pass down on the west side of the river to 1100 feet below sea level and up again on the east side, rising by steps in Breakneck mountain on the east to an elevation of about 400 feet above the river and at this level a tunnel passes through Breakneck mountain. The aqueduct then crosses the adjacent valley on the east side and thence through Bull hill on its way toward New York City, finally leaving the quadrangle a few miles east of Peekskill. The Popping rock of Storm King. A more serious matter was presented by the strained condition of the granite encountered in 98 NEW YORK STATE MUSEUM certain zones in the shaft and tunnel. At some places the solid granite would pop off in slabs with a crackling sound and would sometimes fall quite without warning. These slabs came off quite independently of any rock structure, even breaking directly across the structure quite as well as any other way. Some of the slabs were thin and came to a sharp knife-edge. Injuries from falls of this kind were numerous and they became a serious menace to the workmen, who had to be protected by timbering or other methods. At one place this popping became so active that the tunnel itself had to be protected from a sort of stoping process developed by this popping rock. Slabs had a habit of loosening and dropping off continuously. If the loosened ones were scaled off one day, new ones would be separated by the next. Thus the danger was a con- stant one. At this particular place stoping of this kind in the roof of the tunnel proceeded to such length that measures had to be taken to stop it by timbering. A steel support was finally installed at this point and was left in place when the tunnel was finished. Even after the tunnel was finished, difficulty was made by this strained rock condition. When the tunnel was filled and put under operating pressure a pronounced leak developed on the Moodna side under Storm King mountain. Upon unwatering the tunnel the con- crete lining at the Hudson river end of the Moodna pressure tunnel was found to be ruptured. Study of the possible causes led to the conclusion that rock strain aided by the bursting pressure of the aqueduct water was the cause, the tunnel at that point cutting through a strain zone at too shallow a depth to remain stable with the abnormal conditions then in control. It was finally remedied by constructing a small portion of this end of the Moodna tunnel, where it joins the west shaft of the much deeper Hudson River pressure tunnel, at a greater depth in order to obtain more stable conditions and a better balance between burst- ing pressure aided by strained rock on the one hand and the load of rock above and its strength on the other. The corrected tunnel has since given no trouble. A somewhat similar condition which was, however, .corrected more simply, was developed also on the Breakneck side. Bull Hill tunnel. Bull hill, or Mt Taurus, forms the second mountain ridge on the east side of the river toward the south and the aqueduct penetrates this from one side to the other at about 400 feet above sea level. The rock penetrated is of considerable variety in a minor way. But there is nothing beyond the complexities esl SMA aki 08% OZ; of OF OO aaa a INIOd LSAM GYVMOL ‘HLNOS SNIMOO7T “ONISSOUD YSAIN NOSGNH 4O NOILOSS-SSOHO Sai 6°G blr [ok 2a ae Les a— ¥ < Bor re gonpanbo uy mo)f fo | uo0a4(q —_» auNSSaud ; -QWINS ZUBUDUIIEY nod ae O19 9721909 yzim parif 2 ayuvsy eu % ; | 1TA - d 97049409 YIM pall \cuaquinyo duuind AuJodwuay | ENNAL SYNSSakd MOSNMV SHE "th ‘ln a cay Se [9 oe i : ee ee PIM BEL & we * yy 05L1 | UO ATY NOS aH ME wage “Lee. ua u3)00- GNV -1ND JSNVYO “Janpanko epi “ANNAL SCV YOENMVaHE YY a40ys 359% L4VHS SS399V [ULL YY YH DIAN fp | YSENVHD CNV bnyd agasquoa fig pasojy LAVHS (LS3M) 34VLNMOG H3EWIVHO GNV L4VHS (1SV3) S3DVNIV¥C LIVHS 3yvidN YAEWNVHD GNV 1I4VHS SMVLNMOG gonpanbo fo fizaodoa yjnf fo ffo-mojg. aluiop jays 3809 abn) fig pasoj9 si yous N gy a3eId GEOLOGY OF THE WEST POINT QUADRANGLE, NEW YORK 99 _ belonging normally to the gneisses and granites already described in _ this bulletin, especially the Storm King granite and the gneisses associated with the Canada Hill type of granite which is more fully developed toward the south. Some of the complexities of relation and variety were beautifully exposed in this tunnel, but there was nothing of extraordinary interest or significance. All are covered at the present time with the usual concrete lining. No unusual engineering difficulties were encountered. The ground stood well and the work was prosecuted with no greater difficulty than in the average granite. Foundry brook section. At Foundry brook, which occupies the depression immediately south of Bull Hill, the ground lies too low to carry the aqueduct at grade, and in the beginning explorations were made with the purpose of determining whether a pressure tunnel in rock could be constructed. It was finally decided to use steel pipe in crossing this valley, but the explorations that were made discovered certain conditions that are of general geologic interest and developed uncertainties which exerted an influence on the choice of plan finally adopted. The usual heavy drift cover was encountered, but this in itself was not a serious matter. The condition that was considered more questionable was the discovery of a badly decayed condition of the crystalline rock, in one of the borings, to a depth of several hundred feet. At first, this was thought to indicate considerable extent of bad ground which might give much trouble in construction, especi- ally as artesian or flowing water was furnished by one of the borings penetrating this zone. It was thought also that an old buried stream channel had been discovered that went to much greater depth than had been expected, but this was entirely disproved, and later explora- tions indicated that the decayed zone is probably very narrow and that it is in reality nothing more than a crush zone following a fault line along the east side of the mountain. The questionable boring passed through drift and then through a portion of the solid hanging-wall side of this crush zone for about 75 feet and then ran into the soft decayed rock of the crush zone, keeping within it from that point on to the bottom of the hole, probably bending out of its true course to keep within the softer ground. No considerable trouble ought to be expected in such a zone in spite of the depth to which decay was found to extend. It would soon be passed through in a tunnel and would probably give no 7 100 NEW YORK STATE MUSEUM more difficulty in construction and in operation than any one of a large number of crush zones encountered at other points along the aqueduct line. As a matter of fact, no unusual difficulties are presented for the construction of a tunnel at this point although at the time these facts were discovered there was less complete confidence in the success of pressure tunnels than came to be felt later. It is entirely probable that at some future time this link will be established in such form also, replacing the steel pipe by a pressure tunnel. An interesting thing in a geological way discovered by such explora- tions is the depth to which decay has reached in these crush zones — and the support that it gives to the interpretation of the general structural habit of the district. The artesian well damage claim. An interesting side issue drawn out of the explorations, and the condemnation of the ground on which the aqueduct is located, was developed at this point. The former owners of the ground where these borings were made, brought claim for extraordinary value when the land was condemned because of the taking of their artesian water supply. This flowing hole, discovered during exploration, furnished water which spouted out of the casing to a height of about 10 feet and it is, of course, excellent water. This ground was not known to carry artesian water before these explorations were made and it would probably never been discovered except for them. Nevertheless a claim was made for something like $75,000 because of the taking of this water supply which, it was held, has unusual purity and is capable of being placed on the market. The defense furnished by the city took the stand that this water-bearing crush zone doubtless con- tinues for a considerable distance and extends into and across the residue of the property still remaining in the hands of the owners, and that it could be tapped by the same process of boring on the ground still retained. The theory was advanced that the water was carried by a crush zone extending for a long distance and was fed by the surface waters falling on the mountainsides farther up the valley. As these waters pass downward toward the river, where the surface is lower and where they are held in by a heavy over- capping of glacial drift which does not allow rapid dissipation, they can be tapped by boring into this underground supply which has all the structural characteristics of a certain form of artesian reservoir. This supply as a whole is not in the least interfered with by aqueduct construction as it was not allowed to enter the | . : | | GEOLOGY OF THE WEST POINT QUADRANGLE, NEW YORK {[®f aqueduct. The boring already made was not only to be abandene¢. - but could be completely sealed. It forms a good illustration of the relation of geological factors to some of the side questions growing out of engineering undertak- ings. Numbers of such questions are encountered, some of which have even less foundation for special claim and it is not at all an easy matter to show what the real situation and relative responsibility is. Garrison tunnel. After leaving Foundry brook, the Catskill aqueduct continues for some distance on the high ground with cut- and-cover construction along the sides of the ridges back of Garri- son toward the south and enters a tunnel through the higher ridge ] which forms the divide between this drainage slope and Sprout brook. Although this ridge is not very high, a total distance of over 2 miles requires tunneling. This section is known as the Garrison tunnel. It cuts typical gneisses made up of remnants of Grenville and injections of granite and diorite, with all the complications characterising this belt. On the map this area is referred to the Canada Hill type because of the fact that this kind of granite seems to be the chief injection material and the largest single constituent. P Parts of the belt carry two or three symbols indicating a mixed origin. It is possible in this tunnel to study the minor structural features of the work in detail and get at something of the association of the different parts making up the average:gneissic belt. It is pos- sible also in this case to plot the jointing with a great degree of accuracy at great enough depth to be practically free from the influence of simple weathering effects. These factors have been plotted on the tunnel profile by the engineers in charge of this work and a typical section of this profile is reproduced as an illustration -and a typical section of this profile will ultimately be made available through the final reports of the New York City Board of Water Supply. None of these features, however, introduces any real problem in the engineering work. Interest from that side attaches to quite another matter, that of an excessive amount of decay of bedrock. At the north end of the tunnel for a distance of about 500 feet the ordinary gneisses forming the bedrock were found to be so com- pletely decayed that the ground would not stand at all. In fact it stood no better than ordinary drift and in some places was much more difficult to keep from running into the tunnel. In this ground the structure of the gneiss was almost perfectly preserved, but the whole mass was soft and in places so completely leached of its quartz content that it could be cut with a knife or picked out with the 102 NEW YORK STATE MUSEUM fingers. The whole section of the tunnel had to be timbered right up to the very face of the workings, and the ground gave so much trouble that the work was slowed down and became more than usually expensive. It took the greatest ingenuity and care to carry on the work. Certain patches or streaks were hard, but these were . not of sufficient prominence to dominate and materially influence the behavior for the first 500 feet. Substantial rock was entered at about that point and gave little trouble except at two or three © crush zones where a badly decayed condition was encountered even at greater distance from the surface. The special geologic interest which attaches to this occurrence is involved in the origin and distribution of this decayed rock. There is no good reason to conclude that such decay as this is postglacial simply from the fact that glacial drift lies immediately above it. As a matter of fact there must have been a very great deal of this kind of residuary material previous to the glacial erosion, most of which has been removed, and, after mixing with other materials, has become the drift soil. There is no reason, however, why cer- tain protected places should not still preserve patches of such residuary matter. They are seldom seen, of course, because of the almost universal cover of drift, but in such a piece of work as the aqueduct where continuous trenching or tunneling was car- ried on across the whole district, numerous places were found where such decayed material is still to be seen in its natural position. It is common in crush or fault zones along which underground cir- culation is encouraged, and in a few places borings have discovered such a condition to a depth of several hundred feet. One such occurrence became of practical significance at Foundry brook, as noted under text head. Superficial material of the same sort is more seldom seen, and this exhibit at the north end of the Garrison tunnel is considered to be the best illustration yet discovered in this region. The fact that exactly the same type of rock is perfectly fresh at other places both where it is fully exposed and also under drift cover is complete proof, all other conditions being essentially the same, that the decay is not postglacial. Otherwise decay of this sort would be much more general than it is. But if it is of preglacial origin, then there is no possibility of foretelling its development and extent, as it is directly related to the irregularities of quality and physical condition of the rock along which decay has been easy or difficult. GEOLOGY OF THE WEST POINT QUADRANGLE, NEW YORK 103 The fact that such material is occasionally encountered introduces an engineering factor, which, previous to these experiences, was } generally overlooked. This is the possibility of encountering decayed rock of bad working quality, even after passing through the drift cover on high ground and in positions not usually considered ques- _tionable. As a matter of fact, good behavior was largely taken _ for granted in this case without much exploration, and it was only _ after encountering the difficult ground in actual construction that _ its quality became known. It is a striking thing in this case that _ the ground has a northwest exposure and it would appear that such a place high on the valley side should be completely denuded of such superficial material. That such is not the case, however, is a simple fact and it is not the only one discovered in a similar position. Sprout brook valley section. At Sprout brook the aqueduct reaches a very narrow valley much too low for crossing without some special structure and too narrow to allow a very economical pressure tunnel plan in bedrock. Before the rock conditions were fully determined, however, explorations were made with the idea of determining whether the pressure tunnel method would be feasible The rock floor was found at considerably greater depth than the present surface, the whole bottom of the valley being occupied by limestone standing practically on edge. Gmneisses and granites occupy the sides of the valley and no unusual structural features were discovered. As far as engineering requirements and working conditions are concerned, the rock tunnel is an entirely practical method. That plan was abandoned, however, in favor of steel pipe because of the more economical construction by that method. The tunnel would require a great depth of shaft at either side and that item thus becomes dominant in the total cost, being as great for this short structure as for a longer tunnel. This makes the cost of such a short section quite out of proportion to the other adjacent parts or equal lengths of other pressure tunnels. On the other hand, since the drift fill in the valley brings the floor up to 150 feet elevation, steel pipe could be used to practical advantage. This is an especially good illustration, therefore, of the working of quite a different principle from that of geological interpretation or even of direct engineering questions in the matter of selection of design for a piece of work. The controlling factor in this case is relative cost. 104 NEW YORK STATE MUSEUM Peekskill valley section. The aqueduct after tunneling through q Cat hill reaches, at the western edge of Peekskill hollow, a much ~ broader depression than Sprout brook, where again some pressure structure had to be selected. Explorations were made here also on a comparatively large scale to test the amount of drift cover, the -rock profile of the valley and the quality of bedrock. These data, together with a drawing illustrating the suggested rock structure may be found in N. Y. State Mus. Bul. 146. This valley is occupied by a down-faulted block of the Hudson River-Wappinger-Poughquag series crowded together so closely that the folds are essentially isoclinal and the beds stand on edge across the whole valley. Such a condition introduces no special difficulty in itself, but exploratory borings proved that in the lime- stone beds particularly the circulation of ground water has materi- ally weakened the rock. Comparatively friable material was recovered in many places at considerable depth. These explorations were made at a time before the interpretation of such conditions had become standardized by observation and com- parison of the behavior of such ground in the tunnel construction. In the beginning there was much greater fear of the effect of certain natural conditions and less question of others than they have proved to deserve, and it took several years to put some of them in their true relation. In some places, therefore, where questionable conditions were encountered, an alternative design, wholly avoiding the question at issue, was adopted as the safest procedure. This was doubtless the dominant factor in the decision to use steel pipe for the pressure section crossing Peekskill valley instead of the pressure tunnel in the rock, which could also have been con- structed. It was also true that the steel pipe could be laid more cheaply in this section, but this was hardly the governing factor in this case. Those who have had much experience with the behavior in various tunnels since that time, and also had opportunity to check up on the original borings, know that borings are readily misinterpreted. Underground conditions are easily overempha- sized or underestimated. It should be said, however, that as these qualities and behaviors have come to be better understood, the con- viction has grown that a rock pressure tunnel would be entirely practicable in such ground as this. Perhaps tunnel construction will | be resorted to at some future time if repairs or replacement of the pressure pipe should be required. The Peekskill valley exploration, therefore, is of interest to the Sprout Brook siphon of the Catskill aqueduct. The dump on the hillside is a spoil bank from the grade tunnel emerging at that point. A steel pipe makes the connection across the valley, and a cut-and-cover section then leads off to the left. The steel pipe is imbedded in concrete and the whole covered with earth. GEOLOGY OF THE WEST POINT QUADRANGLE, NEW YORK 105 geologist for two reasons: (1) it shows with accuracy the struc- ture of this most interesting down-faulted block with quality and _ condition of rock that could otherwise not be determined, and (2) it illustrates an engineering problem where uncertainty in the _ interpretation of the conditions discovered led to the adoption of _ anew plan, avoiding the whole question. HISTORICAL GEOLOGY General Historical Outline In the Adirondacks no formations are known older than the Gren- ville. This seems to be true also of southeastern New York, and there is no great doubt but that the formations designated as Gren- ville in these areas are essentially of the same age as those of the type areas in Canada. Unless this correlation is accepted, there is no possible way of determining even approximately the position of the oldest formations in this district with respect to the standard Precambrian system. On account of the very great similarity in character and the relations to other units, there is no serious doubt of the correctness of this name for the oldest metamorphic rocks of the district. Grenville sedimentation. The series was sedimentary and undoubtedly of very large development. There must have been a _ basement on which these sediments were laid down, but thus far no trace of it has been detected. Probably the members of the series which are now found represent only a fraction of the whole series, presumably the uppermost members, and the igneous invasions have destroyed not only the basement, but also considerable portions of the original sedimentaries. _ Judging from the quality of the formation still preserved, in which numerous limestones of varied prominence occur, the deposits must have developed under conditions favoring much shifting of sedimentation between lime deposits and clastic sediments. Perhaps they were marginal sea deposits into which the fluctuating streams brought much detrital matter. In which direction the land areas of that time lay, or what the general geographic distribution of land and sea was, 1s not indicated by the data now available. If, how- ever, the Manhattan-Inwood series is considered as part of the Grenville, its heavy development toward the south would seem to indicate that the land areas probably lay to the west. The largest development of limestone clearly belonging to the Grenville age occupies Sprout Brook valley and may be traced for 106 NEW YORK STATE MUSEUM several miles. Exactly how thick it is can not be determined, but it is at least several hundred feet. It fills the whole width of the valley at one of its widest points, fully a quarter of a mile wide, and, although folding may have caused considerable duplication of strata, it is difficult to avoid an estimate of more than 500 feet. The only other occurrence in the Highlands region comparable to it is the Franklin limestone in New Jersey which has a still greater develop- ment, perhaps more than 2000 feet. The only other limestone formation of similar size in the region is the Inwood limestone, farther south, which attains a thickness of at least 750 feet, and has a very extensive distribution from the Highlands to the sea. If the Manhattan-Inwood series is really of Grenville age, then this Sprout brook occurrence may be simply an outlier of the Inwood, as was assumed at one time by the senior author, and may thus represent the much sought extension of that series toward the north. Although these two limestones may be traced to within a few miles of each other, their characteristics are so noncommittal that it is not considered fully proved that they are the same. There is no question, however, that the conditions of Grenville time were such as to favor occasional developments of limestone of great thickness, and it is also certain that shales and sandstones or arkoses and sediments of considerable variety were laid down in an appar- ently conformable series of great but undetermined thickness. This must have occupied some part of Huronian time, a period of great sedimentary development. But the Huronian was a great complex and, in some regions, is represented by several series of formations with unconformities between them. To which of these the Grenville of this area belongs is quite unknown. Grenville metamorphism. Subsequent history to the end of Precambrian time includes metamorphism, igneous intrusion, and erosion. Some of the steps are clear enough to warrant definite statement. Many others are so obscured by succeeding modifica- tions that a complete history can not be unraveled from this region. Doubtless, however, a better history than we now present can be written when the full meaning of some of the confused structures and other criteria can be determined. For example, it is still a point of great uncertainty how much of the extensive and profound metamorphism of certain formations is due to regional dynamic metamorphism rather than to contact influ- ences, or whether it is possible by igneous intrusion alone to produce a recrystallization and a structural habit so nearly identical with ‘JUS dy} Je aiINjoONAWs peppeq A]suos}s sIOW 9Y} YPM Jey] st UB} peIz1} -IUkIS I1OUI A]QIOPISUOD SI OPIS }fe] 24} Je YOOL oy, ‘“punoise10f [e1jUsd oy} UI OsTe WMOYS ST dinjon.ys pedioursd ay} Oo} joryesred yMeZ ysn4zy} e Jo Seip sayy, “Woe peppeq-uryy [ensn sy} surmoys ‘SsIdUS I[[AUeID) pojefur pue poziueIS Jeymowos ‘pappeq ‘esoysiyos ‘poyeesys ‘popueq eordsy, GEOLOGY OF THE WEST POINT QUADRANGLE, NEW YORK 107 that of typical regional metamczshism that they can not be distin- a guished. If, for example, this latter possibility will hold, then it _ may be that the Grenville did not pass through a period of regional metamorphism before its igneous history began. But if, on the contrary, igneous invasion alone will not accomplish this type of _ transformation, then it is necessary to make allowance for a greater period of time, and a whole epoch of dynamic and earlier history than would otherwise be necessary to assume. The writers of this bulletin, appreciating fully the probability that igneous influences are capable of accomplishing profound results, and that in this district igneous phenomena and effects are much more prominent than dynamic effects, still hold that certain types of metamorphic phenomena are not exactly duplicated by igneous methods. We believe that strong schistose development of a series of rocks, with normal distributicn and relation of minor structures, indicates dynamic metamorphism as the fundamental cause. A closely folded series ot strata with strongly schistose structure ought to furnish the conditions favorable to just the sort of effects produced by the later igneous history more successfully than rock in any other condition, and especially better than simple sediments essentially undisturbed. We regard it as practically certain, there- fore, that the Grenville passed through a period of regional metamor- phism and folding previous to its chief igneous history. This period doubtless belongs to the Huronian also and it may very well be that a very great length of time even for Precambrian epochs has been covered. If the Manhattan-Inwood series is included with the Grenville it is all the more certain that dynamic metamorphism belongs to its earlier history, but the uncertainties of this series make it valueless as a point of argument on this question. To accomplish regional metamorphism of the sort suggested would require that these strata lie under a load of other sediments, and thus a great sedimentation history preceding metamorphism is indicated. Metamorphism was, we believe, caused by folding which transformed the original sediments into foliated types; in short, a great variety of schists, phyllites, quartzites, graywackes and lime- stones. The structural character assumed in that period both in a large and small way has guided or at least has influenced all subse- quent structural development. This folding was followed or per- haps accompanied by erosion, but whether the area was again the seat of sedimentation during the Precambrian is not indicated. 108 NEW YORK STATE MUSEUM Some have thought that the Manhattan Inwood-Lowerre series are Precambrian sediments corresponding to this later point in the column, but, if they are not, then there is nothing known after the Grenville. tate ~Post-Grenville volcanism. To this period belongs a complicated igneous history, and the results are so confused and overlapped that — it is impossible to determine all the steps. It is clear that there has been repeated igneous intrusion. The largest and most fundamental step, however, was the development of a great granite bathylith which seems to have undermined a very large area of which this district is simply a small part. Its many successive stages of activity, accomplished most of the complexity of the Highlands region. Not all the igneous representatives are granite, however, and there is a wide range in the age of individual units; but the most reasonable conception, and the most important one for a work- ing understanding of the history of the district as a whole, is that which connects the greater part of the igneous history with the normal development of a single great bathylith which was itself undergoing extensive changes for an exceedingly long time. Probably the various individual units, distinguished now by their petrographic quality and which differed originally in capacity to metamorphose country rock, are essentially differentiates of the same plutonic mass. Perhaps one sees in such a regional occurrence an illustration of both recurrent activity and continued differentiation. In no other way can one feel justified in attempting to correlate the igneous formations of this district with those of such widely separated regions as northern New Jersey and the southern Adiron- dacks. It does not seem reasonable, otherwise, that in such a number of cases the petrographic habits would be similar enough in these separate districts to indicate identity and that they should match as perfectly as they do. Igneous invasion in widely separated localities could not be expected to present so many points of similarity if there were not one control for all the districts. This control might very well be the successive differentiation stages of a single great bathylith from which the different igneous members came. If this conception is taken as a starting point, then the suggested correlations look reasonable enough, for a particular type of activity might develop in all the regions affected a similar igneous expression. After an epoch of comparative quiet, presumably with continued differentia- tion, a rejuvenation of activity might normally be expected to exhibit a similar expression again in whatever districts this new Plate 51 Massive granite of the Canada Hill granite type exposed by excavation trench for a cut-and-cover stretch of the Catskill aqueduct at Continental- ville. (Compare with plate 50 which is the commonest associated type). These are practically all gradations between the simple massive habit of this gran- ite and the plainly bedded structure of the clearly distinguished Grenville sediments. 2 e2) cae «| Ne ’ Ye , ¥ pee he % ~~ ’ \* GEOLOGY OF THE WEST POINT QUADRANGLE, NEW YORK 109 outbreak is found. Thus it might happen repeatedly, each time with some prospect of finding similar igneous behavior and to some degree similar petrographic quality in widely separated localities. Such a result, it seems, would be most unlikely without some sufficiently widely distributed, very fundamental, deep-seated single unit to be regarded as the chief manufacturer of the whole igneous history. Only on such a basis do we feel any confidence in suggest- ing the correlation referred to in detail in a later paragraph where the Canada Hill granite of this area is correlated with the Losee gneiss of New Jersey and with the older granite of the Adirondacks or when the Storm King granite of this area is correlated with the Byram gneiss of New Jersey and the Syenite series of the Adirondacks. Such a genetic connection of the principal igneous members should develop the intimate mineralogic and structural gradations and con- fused and obscure transitions, which characterize many of these units, and it ought to yield a number of minor units of related origin, but with very great mineralogic differences. Such gradations and confusions ought to be expected, under the condition assumed, because the members are all of the same origin and form a genetic series between which there are no breaks beyond such as develop marginally during stages of quiescence or where successive indi- vidual apophyses invade country rock as separate units. All the older granite members, therefore, of this quadrangle seem to belong to a single igneous history and are simply the different expressions connected with the development of a single bathylith. To this particular history belong the Canada Hill, the Reservoir, the Mahopac and the Storm King granites. Doubtless also some of the more basic rocks are of the same origin and represent extreme differentiates only. Even some of the magnetite bands or magnetite- bearing pegmatites are probably of the same connection. It is not clear, however, that this is the very oldest igneous history. There are basic gneisses, essentially dioritic in composition, intimately associated with the Grenville that exhibit the schistose and gneissic structure more strikingly than most of the granites, and it is probable that certain of these dioritic units are older than the first granite. These may be referred to under the general term Pochuck diorite. _.No good means of determining how much of a break there is between them has been discovered. The best evidence that we have is in connection with the Reservoir granite and the bands .of dioritic gneiss developed in the vicinity of Peekskill and further to IIO NEW YORK STATE MUSEUM the northwest. It is clear in these cases that the Reservoir granite cuts the gneiss and also includes many xenolithic blocks of it, and it is clear also that these blocks had a complex structure mee their inclusion in the granite mass. It seems allowable, therefore, to postulate an igneous history of some sort earlier than the great granite invasion and to credit at least a part of the dioritic gneisses to this time. Acting on this evidence, in the tabulation of formations and in giving the succession of events, we have placed an igneous epoch with development of bases injections between the time of Grenville regional metamor- phism and the great granite invasions. Again at a later time, apparently after the great bathylithic mass had entirely ceased to function, there were igneous developments of a quite independent nature. One of these was the Cortlandt series of norites, gabbros and granites in the Peekskill vicinity, which probably belongs to a later period and not to the Precambrian at all. As a matter of fact, however, the age of the Cortlandt series is not known. There are, however, smaller units of Precambrian age repre- sented by dioritic and basaltic dikes, perhaps best referred to as basic dikes, which cut all of the formations up to the Cambrian. They are particularly abundant in the Storm King granite and asso- ciated gneisses. What relations these have to the larger series is quite unknown. They are clearly Precambrian since none of them cuts the Poughquag or Cambro-Ordovician series although they occur abundantly in the vicinity of the remnants of these formations. It is not beyond possibility, of course, that these dikes are repre- sentatives of the final stages of the same great bathylithic mass, but their strikingly different habit leaves that matter in complete uncer- tainty and the best that can be said is that they are much later and apparently independent. A very extreme type of basic rock was found at one point in the quadrangle, essentially dunite. Only two specimens were gathered, both from the same occurrence, and the relation to the country rock is not very clear. Portions of the dunite are extremely sheared and deformed but beyond that there is no help toward a correlation. There is undoubtedly still greater detail of Precambrian igneous history than is indicated in the outline above. Units have been seen in the field which are not readily matched with any of the fundamental ones which form the basis of this statement, but it is believed that they are in all cases incidental or minor developments A Hi h 16S SSS ‘OHIURIS SUN], WI0}S ote “dotojnO 94} FO jivd [es}Us. oy} Ut podojaAop jaa Ayjeroodsa ‘suorj10d Joys] OATSseU oy} pue ‘oIUeIS [TIFF Bpeued prosstous ole “Tout -WeY IY} Je 19}U99 9Y} UT sayojed UL pue 4ystt oy} 3e UoT}I0d oy} FO Jsowm dn suTyeuUr YOOI poyPe.tys A]JUIEF dy} “ULSIIO UT d[[IAUaIN Pozi}UeIs st jay OY} Je Uo10d oyTpeq poinjon4ys sense sy OQASHYUL oTUeIS SUIN] WI0}G oY} FO Ulds1eUT Aj1oJsva oY} TOU ISpI1 YOoUyYPoIg JO jsva peOI 9}v}s oy} suo;e do19jno uy ‘URIS Surf w10j}g Aq ynO o}ULIS [[IF{ epeue) poyeets pue sorypdtowejou o][I\uetn poziquedsry GEOLOGY OF THE WEST POINT QUADRANGLE, NEW YORK III or variants and that they are insignificant in comparison with the principal factors given. Whatever complexity of structure or quality they develop and whatever gradation or relative sharpness of relation they may show in the field they do not in any case mate- - rially conflict with the explanation given, nor do they suggest a definite modification of the history and principal stages. Precambrian erosion. It would not be possible for the qualities of rock and the structures represented in this district to develop except at great depth. All the phenomena represented in the Pre- cambrian, except that belonging to the original deposition of the sedi- ments themselves, are of a deep-seated type. How deep, no one can tell, but probably many thousands of feet. What the surface ex- pression was like, no one knows. There may have been and probably was volcanic activity, but all of this has been eliminated by the erosion which followed upon the completion of the igneous history. Judging from the relations of the rock at the unconformity, between the Highlands series of gneisses and the Poughquag quartz- ite of Cambrian age, the region was worn down to a comparatively uniform surface. This surface is particularly smooth wherever exposed in this quadrangle and it would be allowable to assume that planation by erosion was very perfect and that essentially a peneplain was developed across the irregularities of the Precambrian series. This erosion cut down into the granite thus removing in many places all the overlying rocks and beveling across the representatives of every stage preceding. This may mean that a large amount of deformation accompanied the other transformations of the Precam- brian history, both faulting and folding. But except for prominent shear zones, some of which appear to date back to this period, there is no other evidence beyond that exhibited by the unconformity just referred to. It is clear in any case that an immense length of time subsequent to the last igneous development must be represented in this erosion interval. Cambro-Ordovician sedimentation. Whatever the conditioas were under which erosion of the Precambrian series was completed, it is clear that sedimentation began with a clean swept floor on which remarkably pure quartz sands were developed. There is nowhere any development of conglomerate and nowhere much mixed or arko- sic material such as might reasonably be expected from the erosion of a granite gneiss area. This fact makes one suspicious of the source of the material and the conditions under which these rocks developed. If developed from the gneisses and granites directly, Li2 NEW YORK STATE MUSEUM no such formation could be accounted for without complete weather- ing of all rock and the removal of everything except the quartz. If done in this way it is difficult to account for the rounded condition of the grains and the extreme purity and the failure to find any con- glomerate facies. Perhaps the most consistent explanation is the assumption of an intermediate source, that is, a series of sedimentary formations, formerly covering the gneisses which has been destroyed in the making of the Poughquag and its associates. Such a formation, of course, if it carried sandstone or quartzite, would be capable of fur- nishing supplies consistent with the development of such formation as the Poughquag. The Manhattan-Inwood-Lowerre series might meet such conditions. It is particularly illuminating, therefore, to observe that the coarser members of the Hudson River series are made up chiefly of lithic grains instead of mineral fragments. In other words, the grains are largely complex rock fragments including fragments of slates, phyllites, schists, dolomites and quartzites. These are all fragments of some older somewhat metamorphosed sediment- ary series which was largely destroyed to furnish the sediments of the Cambro-Ordovician. There is no escape from the conclusion that such modified sediments were available because the fragments can have no other interpretation. The only question, of course, is whether any remnants of such a series are still to be seen. Unless the Manhattan-Inwood-Lowerre is such a series, there is no hope of finding it, but the series mentioned is quite competent to furnish just such supplies as are needed. The present exposures are more completely metamorphosed than are the grains found in the Hudson River series, but if one assumes that in Cambrian time only the uppermost members were exposed and that it was these portions which furnished the materials for the sediments, this discrepancy does not seem at all disturbing. It is entirely possible that there were sandstone members available from which the Poughquag supplies were derived. It ought to be expected also that the upper members of the Grenville floor, above the present igneous intrusions in which pegmatites are so prominent, had large developments of vein-quartz, representing the end products of igneous injection. This would furnish large amounts of addi- tional quartz when these overlying rocks were destroyed. Although there are few fossils, it appears that the Poughquag was laid down under marine conditions, for fragments of Trilobites have been found in this formation on the north margin of the High- a a a ee a a ee ee eee ee ee eee ee ——— GEOLOGY OF THE WEST POINT QUADRANGLE, NEW YORK I13 lands. It appears also that the marine waters deepened and condi- tions of deposition changed to such a degree that a thousand feet of limestone was deposited, representing the Wappinger. Certain beds of this series carry marine fossils. Whether there is a break anywhere in the series does not appear in the rocks in this quad- rangle, but whatever there may be is not a real unconformity be- cause in all essential respects the series is conformable and con- tinuous. Above the limestone an immense thickness of slates, graywackes and sandstones were developed which is known in this district as the Hudson River formation. The source of this material was undoubtedly some earlier series of somewhat metamor- phosed sediments as already indicated. The deposition of this mem- ber, whose thickness is not known, must represent a shallowing of the sea and perhaps even occasional delta deposit conditions, but marine fossils are found in certain layers to the north and the struc- tural behavior of the rock as a whole would lead one to suppose it to have been deposited under water and’ with good sorting. Post-Ordovician revolution or deformation. At the close of the Cambro-Ordovician deposition the region was subjected to elevation and to the deformation of the Taconic epoch. Such a step would not be determinable, as a separate item, from the structural features of this quadrangle, but doubtless a part of the deformation which might otherwise be credited to the Appalachian stage belongs here. It is probable that the deformation of Taconic time has furnished, through subsequent erosion, the new supplies of sediments of mixed type for the great series of formations constituting the rest of the Paleozoic series. The Devonian bluestones and shales show chiefly lithic grains derived from some older somewhat metamorphosed formation, just as the Hudson River formation did before them. The fact that such grains were available indicates that these earlier formations, probably including the Hudson River, were enough metamorphosed at that time to furnish these grains of slates and phyllites and graywackes of which the Devonian beds are in large part composed. Post-Ordovician erosion. Definite traces of this interval which is well marked a few miles farther north, are not determinable in this area. The best evidence of its existence are the qualities of material furnished to the succeeding formations as indicated in the paragraph above. It is entirely possible and indeed probable that great thicknesses of middle and later Paleozoic strata were formed on some of this ground. Many hundreds of feet of Devonian sedi- TI4 NEW YORK STATE MUSEUM ments ‘still remain in a down-faulted remnant just to the west, form- ing Schunnemunk mountain. It is not reasonable to assume that such a great series stopped at this line. Indeed sediments of this type occur as down-faulted blocks in the Highlands, much farther to the southwest in New Jersey, but in this particular area no rem- “nants are found inside the Highlands belt. That they once entirely covered the area may be assumed, and if they did, it simplifies very much the understanding of the behavior of some of the formations which show metamorphism and deformation inconsistent -with any condition except development under considerable load. Appalachian deformation. Mountain folding with much thrust faulting, is recorded abundantly in territory adjacent to this quad- rangle in rocks of later age than the Taconic deformation. In this quadrangle, however, no later Palaeozoic rocks are preserved, so that the check on the time of the deformation epochs is inadequate. Considering the quality of the later deformation, however, with iis tendency to thrust faulting and the prominence of folding, it seems certain that sonie of the deformation of this area is of the same age as the Appalachian revolution. It is particularly difficult, however, to discriminate with certainty between this and the previous epoch. The tendency is to charge most of these features to the Appalachian deformation, and this is probably correct. The big thrust, for example, along the north margin of the Highlands on the northwest side of Storm King mountain and Breakneck ridge is a type of deformation that one would expect in connection with the Appalachian folding and faulting. The close crowding of the now down-faulted block, lying in Peekskill Hollow, is another that prob- ably belongs to this period, and there are doubtless many others, especially those marking the strong northeast-southwest lines of weaknesses. What appears in these rocks as crush zones and longi- tudinal weaknesses may have appeared at the surface of that time as faults and folds. It is probably not necessary to attempt a closer discrimination than this. It is certain that the Appalachian deformation is strongly represented and it is probable also that the chief weaknesses of the Highlands are connected with that dynamic event. Post-Paleozoic time. No Mesozoic rocks are found in this quadrangle, but they are extensively represented in the quadrangle immediately adjacent on the southwest. The West Point quadrangle almost touches the northeastward extension of the great Triassic block of north-central New Jersey. It is entirely likely also that GEOLOGY OF THE WEST POINT QUADRANGLE, NEW YORK II5 the Cortlandt series of intrusives belongs to Triassic time, although _ exact relations to the Triassic beds in this case are obscure, and the position of the Cortlandt series in the geologic scale is not definite. The make-up of the basal conglomerate and other lower beds of the _ Triassic south of this quadrangle shows derivation from little modi- fied rocks of Paleozoic age and indicates a very profound interval SS ee ea ee ae _ -of readjustment and erosion. Probably part of the West Point quad- rangle was covered with Triassic or later sediments of Mesozoic age which were later completely stripped by renewed erosion. The Triassic deposition was probably preceded and certainly accompanied and followed by great block faulting. Thus it happens that the northwest boundary of this Triassic area is formed by a great fault or series of faults, one of which jis continued into this quadrangle as the west side of the Peekskill Hollow down-faulted block. That there was some deformation in the early stages of the Triassic seems to be supported by the abrupt beginning of conglom- erate made up of dominant limestone and quartzite pebbles undoubt- edly derived from the exposed Hudson River-Wappinger-Poughquag series which at that time must have occupied adjacent Highlands a ground. This period, therefore, was one of denudation of the area under study, but- the sediments were not by any means the only source of material for the Triassic beds. Some of them at the base are very feldspathic and are very distinctly arkoses of disintegration origin without much decay. As development continued, however, alternating sandstones and shales accumulated with better sorting. They probably represent destruction of the Hudson River-Wap- pinger series as well as all the higher beds of Paleozoic Age which i now came for the first time within reach of erosion. Thus it hap- pens that the material furnished is of different quality from that r ft found in the Hudson River shales proper or ir “he bluestones of the Catskills. Whatever of these later Paleozoic rocks may have rested on the Highlands district were also carried away. Mesozoic faulting. By all means the most important develop- ment, still preserved in this quadrangle, belongs to that portion of Post-Paleozoic time known as Triassic and has to do chiefly with block faulting. How much of the total faulting of the district is of this age is again a matter impossible to determine in any considerable detail, except in certain lines. For example, that along Peekskill hollow enters the quadrangle at Tompkins cove, and has such a relation farther to the south as to indicate beyond ques- tion that it is a fault of this time. The one next farther to the west, which has prominent development along the Hudson river, following 8 T16 NEW YORK STATE MUSEUM the Grenville belt, is undoubtedly similar in origin and age. It is not certain, of course, that the total deformation along these lines is of Mesozoic Age, but in some cases there is no doubt that a large amount of the displacement is Mesozoic. Many other fault lines have such uncritical relations that it is impossible to place them in a ‘time scale, but it may well be that a good deal of the faulting trace- able in the physiographic expression of this district belongs to this period instead of to earlier ones. At least it is certainly a mistake to credit even the bulk of the faulting to earlier periods. - A more critical evaluation of the evidence doubtless will support the proposi- tion that all the deformation periods developed faults and in some cases probably the same fault lines were the seat of new movement ; but how much belongs to the different individual deformation epochs is not determinable. The Mesozoic deformation, however, seems to have been of the nature of block faulting and is represented by little and wholly inci- dental crumpling or folding. Such an effect on a small scale might be due simply to slight crowding of the blocks. Faulting of the Appalachian time was dominantly of thrust type. That of the Taconic epoch is less definitely known and largely hypothetical, and those of earlier time are quite obscured by subsequent modification. The greatest prominence, therefore, might be expected to attach to the last two epochs and these might well be separated on the basis of character of deformation, that is whether, on the one hand, essen- tially a thrust with its accompanying adjustments or, on the other, essentially block faulting with little other distortion. This separa- tion might be made more perfectly in some other kind of region than in one of granites and gneiss. In such formations as these, some of the evidences to be expected are either obscure or entirely lacking. Most of the faulting belonging to the Mesozoic seems to have been of Triassic age. This is judged to be true chiefly because there is an obscure development of a peneplain on the gneisses of the High- lands. If much of the deformation were Post-Cretaceous, the peneplain ought to be interrupted and abruptly deformed. This does not seem to be prominent enough to warrant emphasis, but it may very well be that this is exactly the explanation for a curious discordance of peneplain level at the southerly margin of the Highlands. It seems as well established as any feature of this kind ts anywhere that the top of the Palisade ridge from New York City to the vicinity of the Highlands on the west side of the Hudson coincides approximately with the Cretaceous peneplain. This rises very gradually from near sea level at New York City to GEOLOGY OF THE WEST POINT QUADRANGLE, NEW YORK 117 a height of between 600 and 700 feet at Haverstraw. If this plane, ‘which is fairly continuous and very definite, is projected to the High- ands across the Haverstraw- -Stony Point lowland, it would strike the ‘mountain mass of Dunderberg and Anthony’s Nose and adjacent “mountain masses much too low to correspond to any prominent physiographic feature on these mountainsides or elsewhere in the ‘Highlands, except the ground near Peekskill and to the east and ‘northeast of that point. The Cretaceous peneplain of the High- lands, if the tops of the mountains may be assumed to represent that feature roughly, is several hundred feet higher than the pro- _ jected peneplain as thus traced toward the Highlands from the south, and it may be that the only meaning to be attached to this : discrepancy is that some of the displacement along certain lines is of _ Post-Cretaceous Age. _ The writers are inclined to believe that this is the proper explana- _ tion of the abrupt break in planes. Traced to the northeast, the dis- - crepancy in levels fades out and there is no such additional movement _ suggested at all, for the weaker phyllites and limestones come in direct contact with granite and gneiss and are eroded to the same level along the contact without any physiographic expression whatever. i Even the fault zone is not marked by any feature in most places. If _ there has been movement in Post-Cretaceous time along this fault, it is all confined to the extension of the line as it follows the edge of D ihe Triassic fault block toward the southwest. Yet another explanation has been suggested by the studies of Bar- rell+ for the steplike arrangement of erosion planes in the northern _ Appalachians. He argues that advances of the sea have developed these forms as marginal and submarine planation effects in later Tertiary time. With this explanation the faulting or deformation question drops largely out of consideration as no deformation, beyond _ that accomplishing enough depression of the whole region to permit 4 the sea to invade and enough re-elevation to cause its retreat, is ‘necessary. Barrell seems to have substantiated his explanation in the _ region studied by him. We are not able to say, from the facts at our ; command in this particular area, the West Point quadrangle, whether . ; or not marine encroachment should be accepted as the best explana- ___ tion here. Later Mesozoic overlap. It seems to be the belief of the physio- _gtaphers who have studied the New England and New York region 1 Joseph Barrell, The Piedmont Terraces of the Northern Appalachians. ga Am. Jour. Sci. 49:257, 258, 327-362, 407-428. (1920) 118 NEW YORK STATE MUSEUM that in late Cretaceous and Tertiary time there was overlapping far inland on the eroded surface by sediments belonging to the late Mesozoic periods. It is judged, for example, that the Hudson river itself has found its way toward the sea nearly in the particular posi- tion which it now occupies on such a sedimentary series of coastal plain deposits. If this is true, it was probably at the close of Cre- taceous time that the Hudson river found its way across this terri- tory, and continued erosion developed a tendency to a new pene- plain level in late Tertiary time. Not long enough time or enough stability was maintained, however, to accomplish more than the beginning of such a plane in the widening of valleys and the develop- ment of flat bottom in accord with the new base level, while the divides reached up near to the former earlier Cretaceous peneplain. At one stage at least a rejuvenation of the streams was inaugurated by a new elevation of the land and new trenches were cut into the bottom of these valleys. This was accomplished prior to the glacial period. It may be that this last step is more complicated than is suggested by the above statement. One of the evidences of a greater complexity is the occurrence of islands within the Hudson river gorge. It is explained in connection with them that the gorge was partly filled with new deposits, and then when the river was rejuvenated enough to cut down into them, it found itself entrenched in places along the side of the true former gorge in such manner as to be impossible for it to escape and slip over into the old position. It would necessarily thereafter develop a new gorge in that position which would ultimately become a part of the final com- pleted Hudson river gorge. If projecting ledges were cut off in this manner on one side by the abnormally located river, and on the other side by the old channel of the river belonging to a preceding epoch, they would necessarily stand as islands in the gorge. It may be that this is the history of them; at least no better has yet been proposed. During the late Tertiary, these physiographic details were pro- duced and have become a part of the history of the region. The development of surface features as now represented, is the last stage in the history of the region and is regarded as the proper field of physiography. These features, therefore, will be discussed further under that head rather than at this point. Glacial history. The region was subjected to ice invasion in the glacial period and seems to have been entirely covered with ice. Glacial erosion is evident as well as glacial deposits. The result of the glacial history has been in large part a subduing of the relief. — GEOLOGY OF THE WEST POINT QUADRANGLE, NEW YORK II19Q Postglacial changes are wholly of the nature of erosion. There has - been some reelevation of the land so that terraces judged to date from the time of the recession of the ice are now lifted somewhat _ above sea level. On the rocks of such a region as this, however, and even on the type of glacial deposits represented, there is little modification produced in this time. | On account of the fact that the details of glacial history and in large part also of the late Tertiary history are bound up with the _ development of the physiography of the region, the rest of this dis- cussion is included with the physiography. Correlation Problems : Two entirely distinct problems of correlation are presented by _ the formations of this quadrangle. 1 One is concerned with the comparison of the Precambrian gneisses and granites, and the succession of events represented by these units in this district, with other districts where the succession may be either better known or have a somewhat clearer expression. 2 The other problem is concerned with the possible identity of the _ Hudson River-Wappinger-Poughquag series of Cambro-Ordovician sediments, extensively developed north of the Highlands, and the Manhattan-Inwood-Lowerre series of crystalline schists, marbles and quarzites south of the Highlands. In the first problem, that of the gneisses and granites, the areas to be compared lie far apart and appear to be hopelessly separated from each other by intervening formations. In the second case, that of the Cambro-Ordovician correlation, representatives of the two series come within the bounds of this quadrangle and patches of the two contrasted series lie within a mile or two of each other. In _ neither case, however, can the problem be solved by tracing the one series directly into the other and, consequently, correlation must be based on comparison of major critical characters and similarity of history. 1 The Precambrian gneisses and granites. In this problem of _ the Precambrian gneisses and granites it is especially desirable to _ make comparison with the Adirondacks, where not only has a great amount of detailed work been done, but the geology is fairly well established in the same terms that have come into use in the much ereater Precambrian fields of Canada. Similar work has been done also within the Highlands belt in New Jersey, represented by the Franklin Furnace and the Raritan folios. U.S. G. 5. Nos. 161 and 162. £20 NEW YORK STATE MUSEUM The West Point quadrangle lies between these two representative areas, and if there is a definite determinable geologic succession, it would seem to be worth while to attempt a correlation of the prin- cipal members and match the major historical steps. In spite of the greater distance, such an attempt looks more promising for the Adirondacks than for the New Jersey area, chiefly because the suc- cession of events has been more definitely determined there by long- continued work and perhaps the steps are more clearly indicated. Comparison with the Adirondacks. In the southern Adirondacks, the essential items, following the later work of Kemp’ and Alling ® may be listed briefly as follows: a The oldest member — the Grenville This is made up of completely metamorphosed formational remnants of very complex original character, including limestones, shales and sandstones, with a complicated subsequent metamorphic and injection history. Such a series is also represented in the West Point area, not on a very large scale, but with all the variety and complication usually assigned to the Grenville of other regions. It is here also, as in the Adirondacks, the most ancient member of the whole series and has had in general the kind of a history formulated for this formation by the Adirondack geologists. On the basis of essential identity of character, and relation to other members, the term Grenville has been used with the same meaning in this area. There appears to be no good ground for doubt about this correlation. b The oldest intrusives — Laurentian These are said to include meta-gabbro and granitic intrusions and injections which, together with the Grenville, are involved in and modified by all the other members. This division is not so clear in the West Point quadrangle as it appears to be in the Adirondacks. But there are occurrences of similar habit in the area always appearing as injections of the Gren- ville or as gneissic products that appear to be older than the more definite simple granite units that make up the major part of the area. Some of these developments are moderately basic, giving a dioritic facies in many places. This is the Pochuck gneiss, in part, of the New Jersey geologists and the type seems to be very much better represented farther west than in the West Point Quadrangle. *>Kemp, J. F. Geology of the Mount Marcy Quadrangle. N. Y. State Mus. Bul. (in press). * Alling, H. L. Some Problems of the Adirondack Precambrian. Am. Jour. Sci. 48:47-68 (1919) ; VERMOVT 4- Franklin Furnace -US.GS. Folio 161 2-Reritan “ 191 3-Yest Point 4:- Philadelphia " 162 5-dAdirondacks 6-New York City Key map of the principal Precambrian areas related to the Highlands of the Hudson, showing the relative positions of the available geologic folios 122 NEW YORK STATE MUSEUM Its age relation is consistent also, as it seems to be the oldest of the large igneous members. A more pronounced development is of granitic character, such as theCanada Hill type. It is not at all clear, however, where the line should be drawn between the igneous representatives of this more ancient period and those of a later time. But taking the suggestion that these older ones are habitually more intimately intermixed with the Grenville so that they tend to form a series with close gradations and transitions, all of which also tend more strongly than do any of the others to exhibit a true gneissic structure, we believe that this member is represented in the West Point area also. Probably the Canada “ill type of this report is the chief representative (see the petrographic description). c The principal igneous invasion — the Algoman Represented in the Adirondack region by great intrusive masses of gabbro, granite, anorthosite and syenite. Of these, it appears that the gabbro is the earliest and the syenite the latest; but it does not appear that any great dynamic revolution or any marked historical hiatus separates them. The time represented is no doubt very long, but normal geologic evidences are largely lacking except for the fact that these igneous units cut each other and have a determinable succession. Some of the members of this division exhibit rather clear-cut and readily distinguished relations to the older series and even their minor injection phenomena tend to develop more striking lit-par-lit bands than were developed by the earlier invasions. They also are said to involve xenolithic masses of the older rocks in great profusion, but have not as a rule succeeded in destroying their iden- tity or the evidences of their former character. Perhaps the crux of the whole correlation problem, as far at least as it applies to the Adirondacks, is the possible identification of the members of this division in the West Point area. The most striking member, the anorthosite, is certainly not represented, and this is — true also of the gabbro. But it is probable that the granite and the syenite or their close equivalents are represented by the Reservoir and Mahopac granite on one hand and by the Storm King granite, as the suggested equivalent of the Adirondacks syenite, on the cther. The Adirondacks syenite is the greatest of the field units of that region, showing much differentiation whose extent and behavior suggest a great bathylithic source and probability of much greater subsurface extent. It is the one member of this division, therefore, GEOLOGY OF THE WEST POINT QUADRANGLE, NEW YORK 123 _ which would be expected to be represented! in the Highlands if any ~ occur there. ' ‘The different large units were compared with this member, with a ood deal of care and with enough success to warrant the suggestion © bo in petrographic character and geologic position with the syenite of - the Adirondacks. _ d The younger intrusives — Keweenawan (?) Occasional basic dikes ranging from camptonite to diorite and dia- base are said to be characteristic of the Adirondacks, cutting all other _ formations. They are supposed to correspond in age to the Kee- weenawan of the Lake Superior region. Basie dikes of similar general composition and structural rela- tion are also found in the Highlands. They cut the Storm King granite in numerous narrow irregular stringers quite independently of any of its primary or recent structures. These are essentially dioritic in composition, but others of slightly different habit and composition are found at other points. There is little doubt but that these correspond in all essential respects to those of the Adiron- _ dack region and the correlation is, therefore, satisfactory in respect to this division also. e Metamorphics of obscure relation These do not appear to be represented in the Adirondacks, but in the Highlands region a curiously obscure series of schists, crystalline limestones and quartzites exhibit such marked differences from the regular well-known Cambro-Ordovician sediments that it is difficult to escape the belief that they are really much older and properly belong to the Precambrian series. This is the essence of the problem of correlation referred to as the second item in the introductory statement at the head of this chapter, that is, the Hudson River- Wappinger-Poughquag comparison with the Manhattan-Inwood- Lowerre series. This will be discussed under a separate head. All that need be said about it in this connection is that the lack of correspondence between the two districts, the Highlands and the Adirondacks, in this respect does not modify materially the identifications and corre- lations determined for the other members of the series already described. But it does introduce a problem of relative age which is of more than passing interest. For example, the very intimate association of certain igneous members with the Manhattan-Inwood- Lowerre series indicates that at least some of the granite invasions ee ee a . Be . + ui ~~ ia i { , is 124 NEW YORK STATE MUSEUM as well as some of the basic intrusives are in reality younger than this metamorphic series, so that if the age of this series could be determined, it would to that degree fix age limits to a certain amount of igneous history. Likewise, since this same series proves to be most intimately associated with the oldest gneiss, the Fordham gneiss in Westchester county and in New York City, where there seems to be conformity between them, the possibility of greater age for this series than is usually assumed is thereby suggested. The questions raised, therefore, by the confused situation repre- sented in the last item are: (1) Are some of the igneous members, both acid and basic ones, comparatively young, even late Paleozoic, as would seem to be indicated if the Manhattan-Inwood series is itself Cambro-Ordovician in age?, or (2) Is the Manhattan-Inwood series shown to be very ancient— perhaps a part of the Grenville itself — by the evidence of its roughly conformable relation to the oldest gneisses and by its igneous associations ? The enormous development of the Manhattan schist with its asso- ciated Inwood limestone south of the Highlands is of course most disconcerting, and if one assumes that they are of Grenville age, they certainly differ much from the typical Grenville of the Adirondacks and of the central Highlands belt. But they are not very unlike the Grenville of the typical Canadian occurrences. The chief difficulty therefore is not their character, but their sudden appearance, together with the fact that a very similar succession of sediments, the Hudson River slates, Wappinger limestone and Poughquag quartzite, of well-established Cambro-Ordovician age, are developed on even a greater scale only a short distance away. It is therefore somewhat easier to account for the difference in character by some meta- morphic influences, which gave to the series south of the Highlands a greater complexity and more elaborate recrystallization, than it is to find a good structural explanation or reason for a great series like this one being so sharply delimited areally, and the failure to find any overlapping of the two contrasted series. A discussion of the points of the problem, however, in any greater detail is not in place here. (See a further continuation of the discussion on page 128.) f The Precambrian erosion interval. Both in the Highlands and in the Adirondacks, long erosion cutting deep into the metamorphic and igneous Precambrian series, preceded the Cambrian subsidence and deposition, and the first ¥ i i GEOLOGY OF THE WEST POINT QUADRANGLE, NEW YORK 125 _ quartzitic sediments of that new order lie in strictly unconformable relation upon them. Summary of the Highlands-Adirondack correlation. It is on the _ whole a very striking correspondence that one finds in comparing the Precambrian geology of the Highlands with that of the Adiron- _ dacks. Every large historical or sequence division of the more fully studied Adirondacks has been either identified or strongly - suggested in the Highlands. This is all the more striking because q the West Point area was studied quite independently of any such consideration, the whole series of formations and historical sequence having been formulated before any attempt was made at a critical comparison. In the attempt to correlate the Precambrian of the Adirondacks and the Highlands, thin sections of some of the typical Adirondacks granites were studied. The granite-syenite series of the Adirondacks is very similar in most respects to the Storm King granite of West Point. The points in common are: t Medium coarse-grained texture. 2 Gneissoid structure. 3 Abundant microcline and microperthite, presence of pleochroic dark-green or brown hornblende, and (or) green slightly pleochroic pyroxene, and (or) brown biotite, as essential minerals. 4 Apatite, titanite, zircon and magnetite as accessories. 5 Comparatively low quartz content. 6 Absence of evidence of strong dynamic metamorphism, but strain shadows in quartz. 7 Rehealing of fine crush effects in feldspar with quartz. They differ chiefly in the following respects: ‘1 The greater abundance of pyroxene in the Adirondacks syenite. 2 The greater alteration of the Adirondacks syenite. The white Laurentian granite of the Adirondacks resembles the Canada Hill granite of the Highlands. Both have the same medium fine texture and granular structure, slightly gneissoid by reason of the orientation of the biotite. The essential minerals are quartz, orthoclase, oligoclase and biotite with slight microcline, microperthite and garnet. Garnet is more abundant in the Highlands. _ The general appearance of the rock caused by the interlocking arrangement of the quartz and feldspars, the small lath-like crystals of brownish, bleached biotite containing rutile inclusions and the small faintly pink garnet are difficult to describe, but are very characteristic and readily recognized. 126 NEW YORK STATE MUSEUM It is of course quite impossible under the conditions governing the present study to carry the correlation to great detail of identification or to complete certainty. The nature of the formations themselves, together with their history, impose rigid limitations also upon such a comparison ; but it seems possible to affirm with considerable assur- ance that some of the individual members are represented in both districts by essentially identical units. Such identical members, for example, seem to be: 1 The Grenville metamorphic sediments : Grenville of the Adirondacks-Grenville of the Higtilana 2 The Injection granite as well as basic injections, meta gabbros, etc. representatives of the older igneous series. Meta gabbros and granite gneisses of the Adirondacks-Pochuck diorite gneiss and probably the Canada Hill granite of the Highlands. 3 The Syenite intrusive member of the younger series. Syenite formation of the Adirondacks-Storm King granite and possibly Reservoir granite of the Highlands. 4 The later basic dikes. Basic dikes of the Adirondacks-diorite dikes of the Highlands. Comparison with the Franklin Furnace district in northern New Jersey. There is little doubt but that essentially the same series of Precambrian rocks as is represented in the West Point quadrangle extends indefinitely toward the south through northern New Jersey and into Pennsylvania; but it is not at all certain that correlation with the Adirondack types can be so fully determined for those more distant areas. It thus happens that in the Franklin Furnace folio of New Jersey a very different set of terms and divisions are used, and a less definite outline of the historical sequence is indicated for them; but in a general way a certain similarity of history has been outlined for that district also. The following quotation“ covers this point : A. comparison of the geology of the New Jersey Highlands with that of the Adirondacks and eastern Ontario reveals the fact that the Byram, Losee. and Pochuck gneisses have their equivalents in the northern districts, and that in general the three districts are essentially similar. The oldest rocks in the northern districts are crystalline limestones, quartz- ites and micaceous schists that are considered to be metamorphosed sedi- ments. Beneath these and also interlayered with them are augite gneisses that may be mashed intrusive granites or the extreme phases of metamorphism ‘Preliminary Account of the Geology of the Highlands in New Jersey; Bayley, W. S., Univ. of Ill. Bul., v. 6, no. 17, p. 18, Feb. 8, 19009. acre GEOLOGY OF THE WEST POINT QUADRANGLE, NEW YORK 127 _ of arkoses or acid volcanic tuffs. The complex is invaded by gabbros, and by rocks called syenites that are practically identical with the Byram gneiss in New Jersey. _ The principal formations recognized by the geologists working in _ New Jersey are: a The Franklin limestone (oldest) together with scattering remnants of metamorphosed sediments of other compositions such as quartzites and micaceous schists, representing the oldest series but mapped with other larger units. b The Pochuck gneiss (next in age) a basic gneiss of very vari- able habit and probabiy both sedimentary and igneous origin. This is judged to correspond to the basic gneiss development of the West Point area, such as the belt at Peekskill, and to the meta gabbros and associated injection gneisses of the Adirondacks. This type is more pronounced in the Franklin Furnace area than in the West Point quadrangle. c The Losee gneiss (apparently younger than the Pochuck). A series of very variable granite gneisses with gradational relations to almost everything else in the region. It is not certain that any | of the formational units of the West Point area correspond very closely to the Losee of New Jersey; but perhaps the Canada Hill type represents the same general historical step. b The Byram gneiss (the youngest member). This term covers a considerable variety of items according to the New Jersey geolo- gists, but descriptions of its chief microscopic characters emphasize the consiancy of certain mineral make-up and habit that suggest a possible relationship to the Storm King granite of the West Point area and the syenite of the Adirondacks. It is evident, however, if this correlation is correct, that the Byram gneiss formation is more confused in age and structural relation than are its equivalents farther north. Probably a closer correlation can not be made because of the different points of view of the different workers as to the chief formational distinctions and their significance. Summary of the New Jersey correlation. The effort to correlate with the mapped districts of northern New Jersey has not been very successful. Doubtless the remnants of ancient sediments, now heavily metamorphosed and all but swallowed up in the igneous invasions, are the equivalent of the Grenville as used in this bulletin for similar remnants. The Pochuck gneiss is probably also roughly equivalent to certain less prominently developed basic gneisses of the West Point quad- 128 NEW YORK STATE MUSEUM rangle. The Losee gneiss is much more obscure and uncertain as to its equivalents and the Byram gneiss, although made to include a very wide range of expressions, as used in New Jersey, is probably in its simplest form a rough equivalent of the Storm King granite of the West Point area and the syenite of the Adirondacks. ‘ In the West Point quadrangle it seemed at first preferable to assign the basic intrusives resembling the Pochuck to an intermediate position between the Canada Hill granite invasion and the Reser- voir granite rather than to a period older than the Canada Hill. But later study favors the belief that these basic members have different age relations and that the principal basic type to which the name Pochuck gneiss ought to be attached is older than any of the important granites. The best representative is the occurrence referred to as the Peekskill diorite gneiss. In such case it may be that the dioritic-pegmatites and associated magnetites are connected with this member and are older than Canada Hill age. ~ Comparison with the New York City area. There is no doubt but that certain facies of the Fordham gneiss of the New York City district represent the Grenville. There is the same sedimentary origin evident in some of the beds, the clearest being numerous limestone layers. Most of them are not large, but they occur in such relation as to make their origin clear. The associated clastic siliceous beds are much more fully transformed and obscure than the limestones because they yielded much better to igneous injection and impregnation. Examination of a collection of typical material from the Ravens- wood grano-diorite of New York City (Brooklyn) shows resem- blance in a few of the slides to the regular Storm King type of granite. The whole series with its wide range of mineral make-up is believed to be more consistent with the range said to be exhibited by the syenites of the Adirondacks. The Ravenswood agrees with both in one respect, that is, its apparent late appearance in the series of intrusives. In New York City it furnishes pegmatites which cut both the Inwood and the Manhattan and is itself a very vigorous invasion unit, developing elaborate injection and impregnation and syntectic effects. Perhaps to this latter habit is in large part due the great variety of composition shown in New York City although some of it may be due to actual differentiation. Comparison with the Philadelphia area. The Baltimore gneiss of the Philadelphia area is regarded as the equivalent of the oldest eneisses of the West Point quadrangle and the Fordham gneiss of ea en er a ee GEOLOGY OF THE WEST POINT QUADRANGLE, NEW YORK 129 New York City. An intrusive granite is described in United States Geological Survey folio 162 in terms that correspond very closely to the description of the Reservoir granites of this bulletin. The - Wissahickon mica gneiss is doubtless the equivalent of the Man- - hattan schist of New York and the Octoraro schist of the Phila- _ delphia region corresponds to the Hudson River slates and phyllites. _ In that district as in the New York there is an obscure structural _ relation which complicates the task of separating the chief mica _ schist from the younger slate-phyllite formation. The case is - well stated by Doctor Bascom in United States Geological Survey Folio 162. — The problem of possible identity of the Manhattan-Inwood- Lowerre series and the Hudson River-Wappinger-Poughquag. This is the second big correlation problem presented by this area. These two series of rocks (the question of whether they are different is not raised at this point) are typically developed at the two diag- onally opposite corners of the quadrangle. The Hudson River- Wappinger-Poughquag series constitutes a very small border along the north margin for a short distance and the Manhattan-Inwood _ Lowerre series has a much larger development in the southeast quar- _ ter of the quadrangle. Only one intermediate occurrence is found in this quadrangle and that is the phyllite-limestone-quartzite series which forms the down-faulted block stretching for many miles along Peekskill hollow. This intermediate strip has often been referred to in discussions of this problem, and has been assumed by some to be the connecting link between the slightly metamorphosed series of the north margin and the very strongly metamorphosed series of the south side. _ These members of the intermediate belt do, as a matter of fact, show > somewhat more crystalline habit than the typical representatives of the north margin but a much less metamorphosed habit than the _typical southern series. It is a rather simple matter to assume, there- fore, that they form the true connecting link and that the very great petrographic and structural differences of the two series are the effects of a greater and greater metamorphism toward the south. The striking thing, of course, is the fact that this down-faulted block, although very near in position to representatives of the Manhattan- Inwood series, maintains its similarity to the Hudson River-Wap- pinger-Poughquag series so clearly as to leave no doubt of their _ identical age, and this in spite of the fact that they are many miles __ removed from each other in outcrop. On the contrary there is a 5 i Site et eee ale aed 130 NEW YORK STATE MUSEUM very short distance between typical occurrences of Manhattan schist of the southern series and the phyllites of the Peekskill Valley. Nevertheless the two are strikingly different in petrographic quality. Since the present condition of both seems to be the result of regional metamorphism, it is very difficult for one to believe that such strik- ing differences could be consistent with so short a distance. Everyone who is familiar with this question has remarked how very different petrographically the two series are, and there is always the strongest inclination to consider them entirely distinct series. As soon as one begins a comparison, however, the difficulty of the whole problem is found to be much greater than was supposed, and a dis- cussion of its essential points covers many other related features. It is such an important matter, however, in this particular area that it is necessary to go into this discussion with some care, and the fol- lowing is a statement of the various points of evidence bearing on the correlation of these two apparently different series. It is realized that the problem can not be solved in this quadrangle but that it probably can be solved by a careful round-about study of adjacent territory carried through for this particular purpose. Such a regional study does not fall within the scope of our present enter- prise, but it is felt that a statement of the nature of the problem and the factors belonging to it will clarify the situation in this district and may be of service ultimately toward a complete solution of the matter of correlation. Comparison of the two series. The argument can best be fol- lowed by arranging in parallel the two groups of factors believed to be essential and suggestive. First, for convenience, the factors that are considered to show identity of the two series ; second, the factors that indicate independence of the two groups. Incidentally the study may serve as an illustration of the kind of problem usually presented in the correlation of obscure crystalline rocks. Principal points of similarity. 1 The two series show great similarity in succession and original character and origin and in comparative thickness of the mem- bers. The upper member is made up of a great but indeterminate thickness of shales, sandstones, graywackes and slates on the north side of the Highlands and a strongly micaceous schist of usually very coarse and thoroughly crystalline habit but similar great thickness on the south side. The former represents the Hudson River shale series and the latter the so-called Manhattan mica schist (also called Hudson schist). a *, _ GEOLOGY OF THE WEST POINT QUADRANGLE, NEW YORK I3I1 _ The next member below in each case is a limestone, varying from or 700 feet to more than 1000 feet, the larger figure represent- ing the Wappinger of the northern series and the smaller figure j Tepresenting the Inwood of the southern series. if _ Beneath the limestone of the northern series is always a quartzite _ with a thickness of approximately 600 feet. Beneath the limestone of the southern series there is in some places a quartzite of very _ moderate thickness, not over 100 or 200 feet at a maximum, but this "quartzite member is usually lacking. It is seen, therefore, that the _ two series are similar in succession and somewhat also in quality barring a great discrepancy in amount of metamorphism. In original _ condition they must have been strikingly similar. | 2 In both cases the formation beneath the whole series is a com- _ plex of gneisses and granites, and in most places the exact relation to this underlying gneissic series is obscure. _ 3 Both series have been very much modified by deformation, so - that the members are folded and sheared, and faulted in a very complex manner. m4 It is frequently stated that the sedimentary formations can be followed through the Highlands in New York, clearly connecting the two sides and proving them to be one formation. On the basis _| of such a statement workers in adjacent districts have assumed an _ identity of the two series which is not necessarily proved. As a _ matter of fact the nearest approach of the two series to each other _ is in the Peekskill valley and the adjacent ground just to the east, _ and even here the structural relations are so obscure that such a _ Statement as this needs to be regarded with considerable caution. _ 5 Description of the variations in the Hudson River series north of the Highlands indicates that to the eastward, from the Hudson river toward the Green mountains or toward the Massachusetts line, the formation becomes gradually more and more crystalline until it exhibits all the petrographic complexity and peculiarity of the typical _| Manhattan schists of the south. This strikingly crystalline condi- _ tion, in what is admitted to be the Hudson River series, removes one of the fundamental objections to its identity with the Manhattan. This objection is that along the Hudson river the wide difference of appearance is a strong support to actual difference in age. The crystalline behavior on the north side, however, toward the east, is not necessarily a proof of their identity because it may be conceived that the Hudson River formation, which is of similar original com- position to the Manhattan, would become, under metamorphism, a tock of very like petrographic habit whether of the same age or not. 8 9 Sioa SOC: a = 132 NEW YORK STATE MUSEUM 6 It is a very disconcerting structural fact that the crystalline series of the south stops abruptly on the Highlands margin, and | although remnants of the Cambro-Ordovician series are found within | a mile to the north, nowhere does one find clear evidence of an over- | lapping of these two series such as would be expected if they are of | ‘distinctly different age and separated by a long erosion interval. This would be understood readily enough if there was clear-cut evi- dence of great thrust faulting and very large displacements, but it is a difficult thing to explain considering the somewhat irregular outlines that are represented. Principal points of dissinularity and criteria indicating difference of age. The criteria given above would seem sufficient to satisfy almost anyone of the identity of the two formations. It is therefore rather surprising to find so many points of discrepancy and to find also that some of the objections are so difficult to explain away. The chief points of this character may be enumerated as follows: 1 There is a very striking difference in general physical appear- ance and petrographic habit of the different members of the two series, especially the upper member in each case. If one confines — the discussion to representatives found within the quadrangle, the Hudson River-Wappinger-Poughquag series is strikingly less metamorphosed than the Manhattan-Inwood-Lowerre series of the _ south, Even if one considers fully the somewhat greater meta- morphism of the down-faulted block of Peekskill hollow, the dis- crepancy still remains very striking, and no student of petrography would fail to discriminate between the phyllites of this locality and the Manhattan schists of Peekskill only a mile away. 2 There is a ditference in thickness of certain of the members, especially an entire lack of quartzite in most occurrences of the _ Manhattan-Inwood series on the south side, as compared with the 600-foot thickness of the Poughquag of the other series on the north side. This is not an impossible condition of course, but it is rather surprising if the two are identical, especially in view of the fact that the 600-foot bed of quartzite still continues in the down-faulted block of Peekskill valley. Such a strongly developed member ought to occur much more extensively than it does south of the Highlands if the two series are the same. 3 The entire lack of bedding in the Manhattan member of the south side is in striking contrast with the rather frequently encoun- tered strongly developed sandstone and graywacke beds of the Hud- son River member of the north side. One would expect, even with SS ee ee GEOLOGY OF THE WEST POINT QUADRANGLE, NEW YORK 133 4a thorough metamorphism, that some of these sandstone beds would _ maintain their identity and be developed as graywackes or quartz- schists; but as far as the writer is aware, there is nothing approach- ing such a type on the south side. There are, to be sure, finer and coarser crystallization effects, some of which are very strikingly different, but the granular structural habit of sandstone or quartzite or graywacke is distinctly absent. To this degree, therefore, the two differ in a suggestive way in original quality as well as in meta- morphism. 4 It appears very plainly in the series of the south side, especially in the Manhattan schist, that igneous injection, impregnation and intrusion is a strikingly prominent and widely distributed feature. Such an effect does not appear in the series of the north side within the district under observation or along the Hudson river. Such a difference might indicate different age, one older and one younger than a certain igneous invasion, but of course, it is possible that igneous invasion coming within reach of the members to the south did not reach those on the north side. Some observers have gone so far as to suggest that the difference in amount of metamorphism may be due not so much to the difference of age as to influence of the igneous invasion which caused extensive recrystallization of those portions south of the Highlands coming within its reach. It is an explanation well worth serious consideration and is along the line of argument recently put forward so ably by Barrell. All that one can say at this stage is that no sufficiently capable and new igneous member is known to which to credit this amount of change. 5 A striking difference of relation to the underlying gneiss series is observable in a few places. This structural discrepancy is the ‘most insurmountable of the objections to the identity of these two series. It 1s perfectly plain that the structures of the Cambro-Ordovician series and of the gneisses as observed on the north margin of the Highlands are entirely discordant. Undoubtedly after the gneisses were developed a very long period of erosion ensued and the basal quartzites represented by the Poughquag were laid down on that eroded floor. Considering the history of the gneisses as outlined elsewhere in this report, it is not surprising that their structures should stand nearly vertical and that the quartzite bedding should lie almost directly across this structure, as it does at certain places near the north margin of this quadrangle. The granites of Storm King and Breakneck do not break through into the overlying series. 134 NEW YORK STATE MUSEUM Therefore, the unconformity is complete and as striking a thing as is to be found between any ancient crystalline series and later sedi- ments. On the south side opportunity is seldom found to inspect the intimate relations of the schist-limestone-quartzite series with the banded gneisses that lie below. Simple undisturbed beds are almost never seen exposed at the surface. In only two places may one see something of the structural relation, and these exposures are somewhat confused and obscured by erosion and cover. .Neither of them lies within the quadrangle under discussion. One is at Ossining in the Tarrytown quadrangle and the other at Hastings in the Harlem quadrangle. Both show unusually good development of quartzite for the south side series, and as nearly as one may judge from the attitude of beds at the present time, it is conformable to the general structure of the gneisses. No better evidence than this of the relation on the south side is at hand, except as exposed in certain pieces of engineering work still farther to the south and east. One of these is at Vahalla in the Tarrytown quadrangle where the surface drift was entirely stripped from the contact on the site of the new Kensico dam. Other occurrences are in New York City, in the Harlem sheet, in deep tunnels, one crossing the contact between gneiss and limestone under the Harlem river at 167th street, New York City, and the other under Delancey street in lower Manhattan, where the same relations were exposed in the city tunnel of the Catskill aqueduct. The striking thing about all three of these occur- rences is the apparent conformity of the bedding in the Inwood limestone with the structure of the underlying gneisses, the quartzite being absent in all these places. Photographs have been taken of this contact and inspection has been made with great care. The best that can be said is that the structure is apparently conformable and, in the best occurrence of all, that under Delancey street, the structure is especially plain and the conformity practically perfect. In none of these cases is there deformation of sufficient consequence to obscure the relation and certainly no deformation of the usual sort could have brought about this parallelism of structure. It is difficult, to say the least, to find a satisfactory explanation for this apparent conformity other than the very obvious one that the beds are in reality conformable. One could readily believe that, in an occasional spot, the structure of the Precambrian rocks might accidentally coincide with that of the overlying series and be misleading, but it is past belief that all of them should be misleading. he SSeS ree —— = an ae ee Ce GEOLOGY OF THE WEST POINT QUADRANGLE, NEW YORK 135 a It is true of course, that there is an elaborate deformation of the members south of the Highlands and that the principal deformation ‘lines of different periods are parallel so that the later folding and faulting follow the general structure of the earlier periods. This tends to confuse the situation very much and, in places where a great _ deal of shearing took place, one might expect to find such a general _ parallelism of structure that most contacts would appear to be con- _ formable. But one can not believe that the minor internal structure i” would be as consistent as it is on that hypothesis. a _ If one were to assume a later granite invasion involving the basal _ member of the Cambro-Ordovician series so as to form an injection gneiss out of the Poughquag quartzite, then one might conclude that _ the Fordham gneiss of New York City, with its apparent conformity with the Inwood limestone, is simply the injected Poughquag and not _ a Precambrian type at all. A comparison, however, of the gneisses _ of the Highlands and of New York City, especially those portions _ referred to as the Grenville in the Highlands, leaves no doubt but _ that the banded gneisses of New York City are precisely the same as the injection gneisses of the Highlands and that there is no room for serious consideration of the Poughquag injection theory. In _ other words, the gneisses of the two areas have similar history and | there is no doubt that in major character they are essentially alike and should be regarded as identical. This leaves the problem where it was before, with this structural dilemma. If the Hudson River-Wappinger and the Manhattan- Inwood series are the same, they must be unconformable with the gneisses in all the different occurrences and in that case the apparent conformity of the southerly series must be a deformation effect. _ But if, as appears to be the case, the southerly series is conformable, _ whereas the northerly one is strictiy unconformable, then. the two _ series can not be correlated and there must be a very great differ- | ence in age. If one may assume for the moment that the southerly series is older and that it represents some of the most ancient sediments _ encountered in the district, then it would not be surprising to find _ that the basal members which were probably quartzose fragmentals in composition had yielded much more readily than the limestones to _ impregnation, injection and absorption by the invading granites. _ These lower members thus appear to have been completely trans- formed into gneisses and actually represent a part of the injected _ Grenville series. They contain numerous smaller beds of limestones _ which clearly indicate that in part the series is sedimentary, but they 136 NEW YORK STATE MUSEUM are so cut up and modified by igneous introduced substances that — their former sedimentary habit is elsewhere almost completely | destroyed. | Such selective effect involves an assumed control of injection by _ the quality of the invaded rock, as the limestones are not heavily “injected or impregnated or even extensively silicated. This is true even of the small interbedded limestones in the Fordham formation. They are not usually badly enough affected to lose their identity in spite of the fact that they lie in the midst of large igneous injections. This can not be doubted for a moment if one has opportunity to inspect the whole series. If such selective control is true for the smaller members, it may very well be still more prominently exhibited by the Inwood. If the small members succeed in reject- ing the invading matters, such a large member as the Inwood might very well escape without granitization at all and with only dikes and pegmatite veins cutting at random through it just as the formation now stands. It would seem to be possible, in other words, that members below the Lowerre might be so thoroughly invaded as to make all the complex gneiss structure that we have in New York City, while at the same time the overlying two members which give less encouragement to injection, might be as little transformed as the Inwood and Manhattan actually are. It is a most striking thing in this connection that the Manhattan schist is many times more affected by igneous matters than is the limestone which lies immedi- ately below. Doubtless selective action of this kind is an important matter in the general process of injection and especially in that phase of it referred to as impregnation. The striking thing is the evidence that seems to be furnished pointing to the possible Grenville age of the Manhattan-Inwood- Lowerre-Fordham series. In other words, if the Fordham is Grenville and the Inwood is conformable with and a continuation of it, and if the Manhattan is a normal succession after the Inwood, then there seems to be no escape from the conclusion that this whole series is Grenville and of Precambrian age. It is most unusual that there should be doubt as to whether a formation is Grenville or Cambro-Ordovician, but there is such a doubt in this case. 6 A sixth point in support of the Grenville age of the southerly series is the fact that in two of the very best exposures, that under the Harlem river and the other under Delancey street, an interbedded layer of quartzose gneiss was encountered at some distance above the base of the Inwood. In one case, at Delancey street, the bed is only GEOLOGY OF THE WEST POINT QUADRANGLE, NEW YORK 137 i 4 or 5 feet thick and perhaps 10 or 15 feet above the base of the - limestone. In the other case, the gneiss is farther removed from the base and is of greater thickness. In both cases, this interbedded gneiss shows injection effects and structure exactly similar to the - gneisses which lie below the Inwood. No way of explaining these facts seems to be satisfying except that there is an actual transition of the sediments and we are inclined, therefore, to accept the extreme interpretation of the Manhattan-Inwood series and cor- relate it with the Grenville. 7 An additional item in the correlation of these sedimentary mem- bers has been gathered from a detailed petrographic study of the quality and source of their primary constituents. When this is applied to the Hudson River formation on the north side of the Highlands, especially in its coarser members, it is evident that the material was originally derived from still older somewhat meta- morphosed sediments. Fragments of sandstones, slates, graywackes, phyllites, crystalline limestones and dolomites. are present, and the quality of the material supports the hypothesis that the fragments were supplied by the disintegration of rocks of similar kind rather than directly from a granitic or gneissic type of country rock. It _ therefore appears that there must have been a series of somewhat metamorphosed sediments within reach of weathering agents at the time the Hudson River formation was being deposited. Remnants of such an earlier series ought to appear as an older more meta- morphosed and more obscure series. Such a requirement is fur- nished by the Manhattan-Inwood-Lowerre series better than by any other formation yet proposed as a supply ground for the materials of the Hudson River formation. If this was not the supply, some- thing else of like type must have been, and it seems much like beg- ging the question to pass over a known thing for something of like character that is purely imaginary. It is realized, of course, that these arguments are not absolutely conclusive, for the fragments found in the Hudson River do not tally exactly with the present quality of the Manhattan-Inwood series ; but, if one assumes that the higher and less profoundly metamorphosed portions of the series was eroded to furnish this supply, the materials ought to be similar to these fragments now found in the Hudson River beds. In short, they should not be expected to have as elaborate meta- morphism as those portions of the Manhattan which were buried deeper and had opportunity for greater and longer continued modifi- cation. 138 NEW YORK STATE MUSEUM 8 It seems impossible to avoid the conclusion that the Manhattan- Inwood series has attained its petrographic and structural character under great load. Its metamorphism and deformation are such as to indicate reorganization under very heavy pressure. Something must have rested upon these members to develop the necessary pressure. The most violent deformation which one sees north of the Highlands has not developed such quality in the Hudson River formation. The chief failure in that case is doubtless not the com- position and not lack of deformation influences, but chiefly lack of load or lack of special igneous influences or both. There was not sufficient pressure to cause complete reorganization. Perhaps also there was not sufficient time, but if the Manhattan-Inwood series is the same age as the Hudson River-Wappinger, the same limita- tion with respect to time would apply to it. If it is the same series as the Hudson River-Wappinger, then it is difficult to conceive of a suf- ficient load in the stratigraphic column represented to account for the metamorphism observed in the Manhattan. The schists are thoroughly recrystallized rather than sheared or granulated and have a prominent development of garnet and other typical reorganization products, all of which point to the same general conclusion. Summary. The items enumerated and discussed on this correla- tion problem may be summarized as follows: A Points favorable to the identity of the Hudson River-Wap- pinger-Poughquag and the Manhattan-Inwood-Lowerre series of sediments and metamorphosed sediments: 1 Similarity of succession and original character. 2 Occurrence of gneisses immediately below. 3 Both series much deformed and modified. 4 Near approach of outcrops of the two series so that one can be traced almost into the other. 5 Reported increase of metamorphism of the Hudson River formation toward the east, until near the Connecticut line it is practically identical in character with the Manhattan schist. . 6 Failure of the structural relation that ought to be expected where the two series approach each other, especially the failure of either entire and actual unconformity or a simple transition. B Points of dissimilarity which seem to support the hypothesis of different age and entire independence of the two series: 1 The strikingly different physical appearance and _ petro- = " Hy : 4 5 ee EN GEOLOGY OF THE WEST POINT QUADRANGLE, NEW YORK 139 graphic habit of the two series, especially of the upper- most members. 2 General absence of the quartzite or lower member on the south side of the Highlands with the metamorphosed series. — 3 Absence of as definite bedding and granular structure in the Manhattan as ought to be expected if it is the metamorphic equivalent of the Hudson River formation. 4 Prominence of igneous impregnation in the Manhattan and absence of igneous influence in the Hudson River forma- tion. 5 Striking unconformity between the Poughquag and the gneisses on the north side, contrasted with the apparent — conformity of the Inwood and the Fordham gneiss of the south side of the Highlands. _ 6 Occurrence of an interbedded layer of typical gneiss in the Inwood limestone member not far above its base. 7 The petrographic make-up of the Hudson River graywackes and other coarse-grained beds, which indicates derivation from the destruction of preexisting somewhat meta-_ morphosed sediments rather than from gneisses and granites, and the fact that the Manhattan-Inwood-Lowerre series would meet the requirements of such a source better than any other now represented. 8 The evidence presented by the metamorphic condition of the Manhattan schist of a greater load of overlying sediments than would have been available if it is the equivalent of the Hudson River formation. On the basis of these facts of observation and statement of rela- ‘tion it seems preferable to continue to regard these two series as distinct and separate and of very different age. The facts are stated in as unprejudiced a manner as possible rather than in the form of a completed argument, knowing that the problem will still be regarded as an unsettled one and that it will necessarily attract the attention of every worker on areal and structural geology in the crystallines of southeastern New York and adjacent districts. That additional data will be furnished from detailed study of neighbor- ing areas is certain, and perhaps they will be more convincing than those listed above, but in any case a fair statement of the facts now available may be of service toward a final and more generally accepted solution. 10 NEW YORK STATE MUSEUM 140 pejzues -aider you A]jUs1eddy (sstaus vied) (qed ul) ssiousd weyploy systyos pue SouoJseull] paeppeqie}Uy (Sessious vied) (qaed ut) ssteus s1oulnjeg ayizyenb 3139077 auoJsaWI] poomuy (e104 ssuojeq A[qeqoid) 4SIYOSs URZeYUL WAL SSTOUS-EOTUL UOROTYESSI soyoq peyues -1ydure pue sauojsueei3 (snoaust Ayaryo) -aideI you Apjueieddy jay, jo esuos Ajqeqoig UIZEMIO (ss1ous uleypioy) sessteus-eied ‘ (euojsaun]T Yoorg SoUOASOUN]-E}2 £9103S qnoidg) sauojseulry eyauL SeqIsoONIy -3Ull] peppeqie}ur pue sezizqienb eqyour SozIzq1End sqysIqos a[qeriea Ayperyo S}SIYOS BOTY sassaus-bleg (Areyueutpas) sjuvuuler o1ydiourezoyy |= sordiowmiejour ajrAuoin SqSTyos-e1eg a][TAUSID JaplO 931zq18nb alisMmo'y 9U0}SSULT] POOMUT qstyos uezyeyUey| l-eider you (Axejueunrpas) A][TAUaIL) 10,27] pe}ues suo SAUL] UlAUPI Ajjusieddy De ee (ssteus yonys0qg) S{SIyOS spus|quioO}yy uy, (jonpoid pextut ssroud auIyuedies JUIOg SUDAD}g | 0} UdAIS doUIeU ¥v) uoI}Aa{UI ayOIp [[PsHeeq suoIsni} 3 auIZUedIesS PURIST U9zk1S ssteus Honyoog |suoroefur o1seq [eUOISeIDQ |-UI oISeq WOI} peAtiop w suOoT}OalUI ISeq [BUOISEDNGQ |SatO 194}0 pur sozljoude WW So} JOUBLU pur sayIyeULsag SISIYOS spus|quioyy | (SNOsUsT 4SoT[IVG) 4 —. a ——————— a aw sstous mi y (sstous uorzoofur) uorjoefur pe}erIoosse B< (axed ut) (jied ut) ssious weyplog (qonpoid pue aqyiueis [[IfT Bpeurg 2 iS sstoud s10UlIyeEg soq1jeuidsd PeXIW BO} UdATS DWEU B) APIULIS ITOAIOSAR O1qqes Bz2IN (snosus7) S45 ssious apusjquioyy |pue soziueid uorjoofuy SsIaus aaso’] sapiqeused ayUeiry (¢) uequemey 5 | | —$ — oo S}PIOIpOUvIS POOMSUDAPY ayIsoyjyiouy Ze ss]ous O1qqey) soqiqeulsad (qonpoid ayUuasG * ayluei1g, joyiueid plossiaua SiayUOX |pexIul BO} UAATS aUIeU B) ayIUPIs BUY WI10}S aqyIuPicy fe} soyiqzeuisog soyiqeuised sstoud weitg saqiqeulsad aydON-oiqqeyy | (Shoaust 104v77) 5 SoyIp seg saxip o1seg saxip o1seg (sn o9uzT) a ——— ALIWUYOANOOND LVAAD asoy eyizqienb a1IgMOT pue 9UOjSAULI] PpoomMuy ‘4sIyoS uUeWeY -uvyy 944 s0"[d sioyyne autos ysnoyye ‘pozues -oider you Ayjus1eddy dyizjzIenb soroiyo auojseull] YeopueueYysS 4SIYOS O1E10JIC) AINNOD YALSAHILISAM anv ALID MUOA MAN Vauy : VIHdTaaVIIHd AHL ayizqienb wepsjog SPFUOOp Se SAT, a[eys atieyofeuer) ayizjienb senbysnog auojsoull] Joxuidde UOIZBULIOJ IAAT UOSpNyT ayizqzienb uoysApie py auoyseully AUUIZE IY a[eys sinqgsurzie jw (Areyuetttpas) UEIOIA Ops10-O1quied SMO VANOUIdV AHL AIDNVuavno INIOd LSHM AHL Agsuaf MAN NUYDHLYUON EE ————————————————————————eeee—ese————————________ nnn EERSTE aqeL UoHVerI0g es1euey nS ne ee ar. Dn ee GEOLOGY OF THE WEST POINT QUADRANGLE, NEW YORK 141 PHYSIOGRAPHY Since the West Point quadrangle lies almost wholly in the High- lands, with crystalline rocks of various sorts making up its whole. substructure, it does not furnish such complete illustration of the physiographic history characterizing the region as would an area containing a greater variety of rocks. The features are, of course, intimately related to those of adjacent districts where pro- nounced and critical physiographic features are represented. Here as elsewhere the fundamental factor in the production of surface form is rock quality and geologic structure. It is, for example, due to the crystalline condition and resistant character of most of the rocks of this locality that the topography is so rugged and the surface elevated so much above the surrounding region. And ridgelike forms with their decided trend in a northeast-south- west orientation for both ridges and valleys result from the rock structure. It is also chiefly due to peculiarities of rock structure and lines of weakness caused by regional deformation that the valleys are narrow and that so many of them are straight. Two structural conditions probably control nearly all the depres- sions. The most general is the occurrence of crush zones following fault lines; the other is the occurrence of belts of rock which are naturally less resistant to weathering and erosion than is the average country rock. The most pronounced of these latter are the lime- stone belts and next to them is the occurrence of Grenville rocks with their varied facies. It is very noticeable indeed that the only broad valleys in the whole district are developed either on limestones or on Grenville belts carrying occasional limestone bands Other topographic expressions are related to glacial influences. Heavy deposits of glacial drift cover many depressions, and, in the southeast quarter of the quadrangle, the drift entirely obscures the rock floor topography and the detail of formational distribution and structure. Glacial lakes are common because of the filling of old outlets and the general obstruction of original drainage lines. Some of the accumuiations are morainic and others are modified drift quite free from any other control than that of ice deposition. Another feature that is somewhat independent of structure is related to the steps of physiographic history, represented by periods of peneplanation and rejuvenation. Thus it happens that there are plain traces of two attempts at base levelling and two or three periods of rejuvenation. Perhaps still other minor steps are represented which may account for some of the physiographic peculiarities. 142 NEW YORK STATE MUSEUM Although a very elaborate statement of the physiographic history would not be warranted from a study of this district alone, yet the major steps of that history are represented by very definite features in the West Point quadrangle. Cretaceous peneplanation. No upland portions of the area are level and the more elevated portions are far from any strict equality of level. Nevertheless it is true that the profile across the quad- rangle on almost any line northwest-southeast gives heights for the principal ridges that fall into fair accordance. Occasional, points rise above the average level and many fall below, yet it is very plain indeed that the average level rises rather uniformly toward the north and northeast. No doubt this would be still more uniform if it were not for large intrusions of massive granite which stand above the average level. Such cases are Dunderberg on the south and parts of the Storm King-Breakneck ridge on the north (plate 54). From such profiles one is impressed with the fact that on the line from Garrison to Peekskill, the average elevation is not far from 500 feet. Five miles northeast a similar profile average gives some- thing near to 900 feet and 4 miles farther, the general level runs about 1000 feet (see plate 51 which shows five profiles on a general outline map of the quadrangle). It is very striking indeed that on such a variety of rock quality there should be so uniform limitation of elevation. Perhaps this is due to the Cretaceous peneplanation. It is not probable that these levels already indicated correspond to the Cretaceous peneplain proper, although some of the higher levels may. It is very probable, however, that the Cretaceous pene- plain in this region is indicated not by the highest point, but by the general level of the wider, more elevated portions. The irregu- larities appearing as depressions below that level represent erosion effects since that time. Subsequent uplift is shown by erosion of the valleys, but in this region the valleys are all narrow and insignificant compared to those both north and south of the Highlands where the rocks are less resistant. Tertiary base level. The Tertiary partial peneplanation seems to be very well marked indeed in the middle Hudson valley north of the Highlands reaching the extreme northwest corner of this sheet along the margin of Breakneck ridge where about 4 square miles of territory lie within the Great valley. No effect of this attempt at base levelling is to be seen in the gateway between Breakneck and Storm King and little evidence of it can be found ee Plate 54 3 a x . z 2 ei = 3 = MUSCOOT LAKE DUNDERBERG MTS, Profiles across the West Point quadrangle 144 NEW YORK STATE MUSEUM until the vicinity of Cold Spring, West Point and Constitution island are reached. From Cold Spring southward to Fort Mont- gomery prominent rock terraces on both sides of the river doubtless mark this Tertiary history. West Point is located in part on this terrace. A considerable area in the vicinity of Garrison and south- ward is on the terrace as well as Highland Falls on the opposite side of the river. It is rather striking that these terraces are so prominent in this portion of the valley whereas they are not apparent at all at the northern gateway or at the southern gateway between Dunderberg and Anthony’s Nose. The reason for it, no doubt, is the fact that the rocks in this intervening belt are chiefly Grenville gneisses, schists and limestones, and on them erosion has accom- plished much more than on the massive intrusive members repre- sented at the other places. The very decidedly different appearance of the valley walls in these different sections at first suggest the possibility that the river did not have its present course at all in Tertiary time at the two extremes of the gorge through the Highlands but did pursue the same course in the intermediate section between West Point and Fort Montgomery. Although it is not probable that such a change took place at this time it may very well be that the drainage immedi- ately following the Cretaceous peneplanation was quite different from the present and that more prominent drainage than is carried at present came down through the Clove creek-Foundry brook depression, helping to develop a topography quite out of keeping with the present importance of the tributary stream draining this broad depression. In this middle section, the river follows the major rock structure perfectly, but elsewhere it does not. It appears, therefore, to be strictly a superimposed stream with only partial adjustment. Minor oscillation. Physiographers have argued in favor of minor oscillation of level in addition to these major movements. It is plain that, subsequent to the mid-Tertiary base-levelling stage, a rejuvena- tion was inaugurated by uplift, and that trenches were cut into the somewhat widened valley bottoms by the streams of that time. This subordinate erosion stage has in most places in this quadrangle entirely obliterated all traces of the former base level, but in occasional stretches, as indicated above, terraces are still preserved. It is possible, that other epochs of depression should also be noted in a complete history. If that is true, deposits ought to have been formed in the Hudson valley across this district, but no trace . -) ETAT: “ . ora. 5 U s i , ‘ . Ned . a. | Sa JOHN M. CLARKE UNIVERSITY OF THE STATE OF NEW YORK STATE GEOLOGIST STATE MUSEUM .) BULLETIN 226, 226. PLATE 55 2 DY Shs? ZZ. ES Pree Z is 2 Sas LLY, x 5 Granite Triassic, Shales and Sandstones Palisade Diabase Sandstones Glacial fill of Manhattan Schist and Pre-Cambrian Gneiss Schist and and Gneiss : : Geiss the Hudson Gorge Inwood Limestone : Limestone A BLOCK DIAGRAM OF THE DISTRICT IN WHICH THE WEST POINT QUADRANGLE IS SITUATED SHOWING THE RELIEF FEATURES AND SOME OF THE CONTROLLING STRUCTURE RELIEF DRAWING BY FREDERICK K. MORRIS—GEOLOGIC STRUCTURE BY CHARLES P. BERKEY. GEOLOGY OF THE WEST POINT QUADRANGLE, NEW YORK 145 of such material is to be seen now, and none is to be seen elsewhere north of the Highlands. | Certain islands within the present channel of the Hudson river, such as Constitution island, Iona island and several small ones, — however, are believed to have a genetic connection with this missing history. It is argued, for example, that the river channel at first passed to the south of Iona island instead of the north side where it is now, and that this channel was established previous to one of these deposition epochs. During that time deposits were laid down filling the gorge, and when rejuvenated the river lodged on the opposite side of the valley from its former position, becoming entrenched there so firmly in the soft deposits that it has held that position ever since Even when the hard rock was reached it kept the new position and the islands have resulted from continued erosion. No better explanation has been given of the origin of several such islands in the Hudson gorge and no equally good structural reason independent of some such history is offered. So far as the features of this quadrangle are concerned, therefore, little direct evidence of oscillation and former occupation of the ground by Tertiary deposits is to be seen, but the indirect evidence of the islands within the inner gorge is at least worth considering in support of such history. Glacial modification. Glacial scour has accomiplished more in the Hudson gorge than at most other places and perhaps some of the change of course as well as form is due to that agent. It has already been pointed out in connection with the discussion of the Storm King crossing of the Catskill aqueduct that glacial over-deepening and widening of the gorge has been proved at that point. It may very well be that glacial ice not only enlarged certain places which formerly were much more restricted, but that, at the time of with- drawal, it also left obstructing drift in portions of former channels that were previously open. Thus it may be that the change of course in the case of some oi these islands is glacial and postglacial rather than Tertiary. The history at least with regard to some of these islands is obscured by glacial scour and glacial deposits and it may be that the position of the river is exactly reversed by this later experience quite independently of the earlier modifications. The present profile on such a spur as Anthony’s Nose is good proof also of glacial modification of form. This prominent projecting mass has been snubbed by glacial ice. 146 NEW YORK STATE MUSEUM No doubt the region was very elevated immediately preceding and during a part of glacial time. But beyond the fact that the river gorge is several hundred feet deeper than the present water level, no’ direct evidence on that point is obtainable. The region has since been depressed, however, somewhat lower than this former level. This is indicated by the fact that the river is drowned. Postglacial changes. Evidence that the river level has changed since the time of the withdrawal of the ice is found in the occurrence of terraces of sand, gravel and associated delta and modified drift deposits at the mouths of certain streams emptying into the Hudson, such as Peekskill creek. The state camp at that point is located on one of these terraces which is just above the 100 foot contour. This agrees fairly well with evidence elsewhere that the difference of level since glacial time is something like 100 or 125 feet for this quadrangle. In the absence of cther conclusive evidence to the con- trary, it may be assumed that it means re-elevation of the land to that amount, the river representing sea level in each case. It is evi- dent, from the behavior of the streams and their accumulations in these terrace materials, that the deposits must have been made dur- ing the withdrawal of the ice and while it was melting. In other words, they were furszished by the thawing ice. Therefore, they mark the immediate close of the ice occupation for this locality. This may be taken as the starting point for postglacial history. Such erosion effects as have been accomplished on the drift are chiefly on the lighter modified drift types and especially on the river deposits which at one time may have largely filled the channel of the river at certain points. Reelevation rejuvenated the streams somewhat and they cut down through these silts and sands leaving the remnants as terraces. Farther back from the river and on more substantial types of drift and on bedrock few changes have been accomplished in this territory. The streams are all small and the modifications are limited to trenching soft deposits and cutting out- lets a little deeper. Some of the lakes of that time have been drained. This amount of elevation also emphasizes the islands in the river, some of which would be entirely beneath the water level if change of level had not set up new conditions. Even Constitution island would hardly be seen or little Stony Point or Iona island if it were not for postglacial reelevation and consequent readjustment of river level. None of the others would ke seen at all. eirogenic represented by uplift and depression, and still others by the very different effect of the agents, ice and water, under the chang- ing limitations of different epochs. With the making of these forms: Ot the geologic history of the West Point area touches the present time. he Ladies 9 aan ral) oney! dele Sis Lervacitad got: Mire cleatormite) seenevianitval hed ‘toy odeguyt paeiceone sic) apres FO ee RERE hires tthe ety a wh orbits baaliieatco ie basis dle! my fas moni 99 HS: toring) it westlt do eenbaad ods ci. “herlsdqort ae Rbk Arorer ttesevert: el) eoadot pers: deo wo ode nema Sieh wat i eee Danco atceteods ii 0 . , ‘ hy Phy / ai Sa 7 * i: an . 4 1 4 a ale 4 . < i Algoman, 122 Alling, H. L., cited, 120 _ Amawalk, 62 Annsville creek, 12 Anthony’s Nose, 10, 11, 87 Appalachian deformation, 114 Artesian well damage claim, 100 _ Ball mill pebbles, 91 Barrell, Joseph, cited, 117 Basalt, 56 ' Bayley, W. S., cited, 126 _ Berkey, Charles P., cited, 20 Biotite-augite nantes 67 Biotite-norite, 67 lock, Adrian, 14 Boyd Corners, 53 Breakneck mountain, 10, 83 Breakneck ridge, 10, 31 Building stone, 82 - Bull Hill, 10, 11 Bull Hill tunnel, Catskill aqueduct, 98 _ Byram gneiss, 19 Cambrian unconformity, 73 III anada Hill granite, 33, 30, 53, 71, 109; description, 52 atskill aqueduct, 11, 13, 20, 90; bul- _letin on geology of, 21; special - note of problems connected with, Hy Wolony, R. J., cited, 20, 22, 86 { = State Survey, 19 onopus hollow, 18 Cambro-Ordovician sediments, 9, 62, INDEX Correlation problems, 119; 138 Correlation table, general, 140 Cortlandt area, 90 Cortlandt gabbro-diorite, 22 Cortlandt series, 2I,. 23, 31, 35, 39, 42, 43, 60, 83; description, 66 Cretaceous peneplanation, 142 Crompond road, 64 Croton dam, 82 Crows nest, I0, II Crugers, 91 Crushed stone, 88 Crystalline limestones, 27, 47 Crystalline rocks, 6, 9; causes of variation in, 30 summary, Dana, James D., cited, 18 Deformation products, 47 Deformation structures, 72 Diabase, 56 Diorite, 56, 67 Dioritic rocks, 27 Discovery and colonial history, 14 Drift, 13 Dunderberg, 10, II, 31 Dunite, 57 Dutchess Junction, 89 Dynamic influences or deformation, 44 Eaton, Amos, cited, 16 Economic geology, 82 Economic resources, mary, 92 Emery, 90, 92 Engineering geology, 82 Engineering undertakings, 92 Erosion feature, 10 general sum- Farmer, Clarence N., cited, 20 Fault system, 23 Faults, 75; Mesozoic, 115 | Fettke, Charles R., cited, 20, 22 149 i50 NEW YORK Fishkill creek, 12 Folds, 80 Fordham gneiss, 20 Formation groups of larger petro- graphic significance, 45 _ Fort Montgomery, 7 Foundry brook, 12, 89 Foundry brook section, Catskill aque- duct, 99 Garrison, 7, 12 Garrison tunnel, 13; Catskill aque- duct, 101 Geography of quadrangle, 7 Geologic formations, 22 Geology, general, 16 Glacial history, 118 Glacial modification, 145 Glacial unconformity, 75 Gneisses, mixed, petrogenesis, hornblende gneisses associated with magnetite veins, 16; structural con- ceptions, 19; general strike, 22; hornblende-plagioclase, 57; in- jection, 59; impregnation, 59; men- tioned, 22, 23, 27, I19 Gordon, C. E., cited, 20, 21 Granite, 19, 22, 23, 27, 119; building stone, 82 Graphite, 91 Gravel, 88 Graywackes, 46, 63 Grenville metamorphism, 106 Grenville sedimentation, 105 Grenville series, 26, 29, 31, 32, 33, 47, 49 Haverstraw, 89 Herbert, Edres, 91 Highland belt, 10 Highland Falls, 7, 12 Highlands, 7; Mather’s description of structural features, 17 Highlands—Adirondack correlation, summary of, 125 Highlands gneiss, 22 Historical geology, 105 Hornblende—-norite, 67 Hudson, Henry, 14 (oh STATE MUSEUM Hudson river, extraordinary features, 10; exact depth of gorge, 11; depth as ascertained by work on Catskill — | aqueduct, 94-97 ‘ Hudson River crossing from Storm — King to Breakneck mountain, | Catskill aqueduct, 93 q Hudson river formation, 46; descrip- — tion, 63 Hudson river phyllite, 43 . Hudson river series, 22, 23, 31, 33, 120 Hudson river shales, 23 Hudson river slates, 21 Hudson River-Wappinger series, 84 Hudson schist, 20 Hudson trench, through the High-— lands, 10 Igneous history, Post-Grenville vol- — canism, 108 Igneous impregnation, 40 Igneous injection, 39 Igneous invasion, 122 Igneous rocks, 27, 48, 51, 64 Interstate Park, 7 Inwood limestone, 20, 22, 23, 85; scription, 62 Inwood series, 23, 31, 32, 33, 47, 120 Iron, 87 Islands, 10 de- Jones point, 88 Kemp, James F., cited, 20, 21, 120 Keweenawan, 123 Kings quarry, 52 Kingston, 14 Lime, 86 Limestone, building stone, 84 Limestones, structural conceptions, ~ 19; mentioned, 18, 22, 23, 27, 46, 47 Location map, 8 Lorillard, Mr, 92 Losee gneiss, I9 Lowerre quartzite, 20, 60 Lowerre series, 23, 31, 47, 129 INDEX TO GEOLOGY OF THE WEST POINT QUADRANGLE Magmatic absorption or syntexis, 38 -Magmatic differentiation, 33, 35 Magmatic movement, 37 _ Magnetite schist, 58 Mahopac, 7 Mahopac granite, 54 Manhattan schist, 20, 21, 22, 23, 32, 43, 124; analysis, 61; description, 60 Manhattan series, 31, 32, 33, 47, 129 Map of the State, published in 1896, 18 Mappable formations petrography, 48 Mapping, method of, 27 Marble, building stone, 84 Mather, W. W., cited, 16 Matteawan, 7 Mesozoic faulting, 115. Mesozoic overlap, later, 117 Metamorphic rocks, 5 Metamorphics of doubtful age, 60 Metamorphics of obscure relation, 123 Metamorphism, 31 Mica, 27 Mineral resources, 82 Mohegan granite, 35, 64; analysis, 66 Mohegan quarries, 83 109; description, with their New Jersey correlation, summary, 127 _ New Jersey folios,’ 18 New York City area, comparison with, 128 Olivine-pyroxenite, 68 Organic rocks, metamorphosed, 47 Oscawana, 58 — Oscillation, minor, 144 : Peekskill, 7, 9, 58 Peekskill creek, 12 Peekskill granite, 22, 35; analysis, 65; description, 64 Peekskill Hollow, 18, 63, 85, 86 Peekskill Hollow creek, Io, 12 151 Peekskill-Mohegan granite, 82 Peekskill valley section, Catskill aqueduct, 104 Pegmatite, 19, 27 Peridotite, 57 Petrographic geology, 290 Philadelphia area, comparison with, 128 Phyllites, 46, 64 Physical geography, 9 Physiography, 141 Pochuck diorite, description, 51 Pochuck gneiss, 19; description, 57 Popping rock of Storm King, 97 Postglacial changes, 146 Post-Grenville volcanism, 108 Post-Ordovician erosion, I13 Post-Ordovician revolution or de- formation, 113 | Post-Palaeozoic time, 114 Poughkeepsie quadrangle, 21 Poughquag quartzite, 22, 46, 86, 112; description, 62 Poughquag series, 23, 31, 33, 129 Precambrian erosion, III Precambrian rocks, 10, I19 Precambrian unconformity, 73 Pyrite, 87 Quartz, 27 Quartzite, 23, 46, 86 Quartzitic gneiss, 58 Railroads, 7 Ramapo mountain escarpment, 23 Raritan folio, 18 Reservoir granite, 53 Revolutionary history, 14 Ridgway, Robert, cited, 21 Road metal, 88 Roads, 9 Rock formations, 29 Rocks, chief types, 26 Rogers, G. S., cited, 21, 66, 90 109; description, Sand, 88 Schists, 22, 23, 27 152 Sedimentary and organic rocks little metamorphosed, 46 Sedimentary rocks, metamorphosed, 47 Slates, 23, 46, 64 so Sronlbyn South Beacon, Io Sprout Brook limestone, 85 Sprout brook yalley section, Catskill aqueduct, 103 Steamboat service, 7 Stewart, Charles, cited, 21 Stockbridge dolomite, 20 Stony Point, 67 Storm King, 10, I1, 31 Storm King-Breakneck fault, 77 Storm King granite, 22, 23, 26, 34, 40, 83, 109; description, 56 Structural geology, 69 Tarrytown quadrangle, 6, 19. Taurus, Mt, 98 Terraces, II NEW YORK STATE MUSEUM Tertiary base level, 142 Tompkins Cove, 84, 89 Tompkins Cove limestone, 92 a Tompkins Cove ec Valley fanle | { line, 78 E Unconformities, Precambrian un- — conformity, 73 a Verplanck point, 85, 80 Wappinger limestone, 46, 84; de-_ scription, 62 ¥ Wappinger series, 23, 31, 33, 120 Washington, George, I5 Water, 89 West Point, 7, 12 ‘ West Point quadrangle, location, 7; — total area, 7; geography, 7; physi- cal geography, 9 ; Williams, cited, 68 Yonkers gneiss, 20 Py an VAs 22g UCU UCT a) ——— a en ee Se my i JOHN M. CLARKE UNIVERSITY OF THE STATE OF NEW YORK BULLETIN 225, 226 STATE GEOLOGIST STATE MUSEUM ( WEST POINT QUADRANGLE IGNEOUS ROCKS Diorites oO i Peekskill Granite CORTLANDT SERIES Not shown Dioritic and Basaltic Dikes Storm King Granite PRE-CAMBRIAN SERIES Pochuck Diorite and Dioritic Gneiss Grenville and Reservoir Granite MIXED TYPES Grenyille and Poohuck Diorite SEDIMENTARY SERIES Hudson Riyer Shales and Phyllites ee | Wappinger Limestone pecs, Poughquag Quartzite Manhattan Schist CAMBRO-ORDOVICIAN AGE Inwood Limestone Not shown Lowerre Quartzite DOUBTFUL AGE AS, = San aoutates eRe SS eee 1, GRENVILLE AGE Grenyille Gneiss and Schists Faults CATSKILL AQUEDUCT Pressure Aqueduct xxx Grade Tunnel -- Ourand Cover Aqueduct —_-~ Geology by Charles P. Berkey and Marion Rice, 1918 ee ene a N. Y. State Museum Bulletin 225, 226. Plate 56 ‘The Palisades of the Hudson Haverstraw Bay Bear Mountain Iona Island ort Montgomery Dunderberg Canada Hill Shawangunk Rapge Fishkill Mountains Storm King Cornwall Newburgh Breakneck Ridge Northern Gateway of the Highlands Crows Foundry Brook and Cloye Creek Valley West Point Military Academy - Bull Hill > a = aes a od ae er | | ’ é : | | N.Y. State Museum Bulletin 225, 226. Plate 56 7 ~ - fm serene er Garrison Constitution Island Cold Spring HUDSON RIVER-HIGHLANDS PANORAMA TAKEN FROM FORT HILL EAST OF GARRISON Photograph by Wm. J. Bresnan, and used by permission of the New York City Board of Water Supply econd-class matter Woveniber 27, I915, at the ae Office at Albany, N. Y, under e a of August 24, 1912. ~ Acceptance for mailing at special rate of postage provided for - in section 1103, act of October 3, 1917, authorized July 19, 1918 a= York State Museum Joun M. Crarke, Director ENTH REPORT OF THE DIRECTOR OF STATE. MUSEUM AND SCIENCE : DEPARTMENT pig “usanian fnatiy, fc® Hy (2 ere x : NS 202420 . “ Clionah Buse” PAGE ; . PAGE See ee 7 | Scientific Papers: ips fe We eae The Tully Glacial Series. O.D. BEE cg Pas ts vg: rena sis ae WON INGELN.. Col cesie us ne Siva Oe ie eee Oe 18 _ Paleontologic Contributions Meee tis cia Sve es 2's 26. from the New York State Mu- d Ethnology. 28 seum. RUDOLF RUEDEMANN_ 63 Department of Science 29 List of Publications............. 131 | ) the Collections. wie caught ac (ape NNSA GAS 145 ; ° = : _ ALBANY _ ¢ THE UNIVERSITY OF. THE STATE OF NEW YORK oe a ee =a — 4 Pe 0 A i = a Sh - ener Fen 3 ee cer tS ee is ei ee TE cme THE UNIVERSITY OF THE STATE OF NEW YORK —s_—~™ Regents of the University With years when terms expire Revised to November 15, ‘I921 1926 Priny T.SExton LL.B. LL.D. Chancellor Emeritus Paka 1922 CHESTER S. Lorp M.A. LL.D. Chancellor — - Brooklyn 1924 ADELBERT Moot LL.D. Vice Chancellor - - —- Buffalo 1927 ALBERT VANDER VEER M.D. M.A. Ph.D. LL.D. Albany 1925 CHARLES B. ALEXANDER M.A. LL.B. LL.D. EGE =, - — - = Taxeig see 1928 WALTER GuEST KELLOGG BA. LLD. — — ' — Ogdensburg a 1932 JAMES ByrNE B.A. LL.B. LL.D. - - - -. — New York 1929 HERBERT L. BripcMan M.A.LL.D. - - —- = Brooklyn d 1931 THomas J. Mancan M.A. -- — - —- — = Binghamton 4 1933 WiLLIaAM J. WattiIn M.A. - - - - - = Yonkers 1923 WILLIAM Bonny M.A. LL.B. Ph.D. - - - —- New York 1930 WILLIAM P, Baker B.L. Litt.D. - - - —- -— Syracuse President of the University and Commissioner of Education Frank P. Graves Ph.D. Litt.D. L.H.D. LL.D. Deputy Commissioner and Counsel FRANK B. GILBERT B.A. LL.D. Assistant Commissioner and Director of Professional Education Avucustus S. Downine M.A. Pd.D. L.H.D. LL.D. Assistant Commissioner for Secondary Education CuarLes F. WHEELOcK B.S. Pd.D. LL.D. Assistant Commissioner for Elementary Education GrorcEe M. Wirey M.A. Pd.D. LL.D. Director of State Library James I. Wyer M.LS. Pd.D. Director of Science and State Museum Joun M. CriarkeE D.Sc. LL.D. Chiefs and Directors of Divisions Administration, Hrram C. CasE Archives and History, James SuLtiIvan M.A. Ph.D. Attendance, James D. SULLIVAN Examinations and Inspections, AVERY W. SKINNER B.A. _ Law, Frank B. Gitpert B.A. LL.D., Counsel Library Extension, WiLL1AM R. Watson B.S. Library School, Epna M. SanpErRsSON B.A. B.L.S. School Buildings and Grounds, Frank H. Woop M.A. School Libraries, SHERMAN Witiiams Pd.D. Visual Instruction, ALFRED W. ABRAMS Ph.B. Vocational and Extension Education, Lewis A. WILSON — TET YY 2) Redes se) Snel A HB fs sins ne The es of the State of New York Science Department, August 30, 1920 Dr John H. Finley j President of the University Sir: I beg to transmit herewith my annual report as Director of is department and to request its publication as a bulletin of the ate Museum. Very respectfully yours Joun M. CLarKE Director Approved for publication ie "ay Oe eS } Os ‘a ? ? Pi sty F ne . : ion a ' Pid , A ‘ ~~ —— _ - = i: aa inf e ed — oe ew York State Museum Bulletin Entered as second-class matter November 27,1915, at the Post Office at Albany, N. Y., under the act of August 24, 1912. Acceptance for mailing at special rate of postage provided for in section 1103, act of October 3, 1917, authorized July 19, 1918 Published monthly by The University of the State of New York | Nos. 227, 228 ALBANY, N.Y. November-December 1919 The University of the State of New York New York State Museum Joun M. CLarke, Director SIXTEENTH REPORT OF THE DIRECTOR OF THE STATE MUSEUM AND SCIENCE | DEPARTMENT | INCLUDING THE SEVENTY-THIRD REPORT OF THE STATE MUSEUM, THE THIRTY NINTH REPORT OF THE STATE GEOLOGIST AND THE REPORT OF THE STATE PALEONTOLOGIST FOR Ig919 INTRODUCTION The work of this Department during the year past has suffered I} giave handicap from the difficulty of adjusting the income of the |) organization to the demands of the research divisions and the proper maintenance of the Museum. Inadequacy of compensation to the scientific employees has resulted in the loss of valuable men who have served loyally and sacrificed bravely but have at last reached the limit of resistance to the temptations of the industrial world. As long as the attachés of the scientific staff are without assurance of a decent living, are forced into situations where they must sacrifice even their Liberty Bonds to make ends meet, there must result not only a loss of the best service which can not be made good, but also a serious impairment of the spirit in which the work is done; a lessening of devotion and enthusiasm and a weakening of the bond of respect which the employee has toward the supreme employer. This relation between the State and its servants is, for this Department as doubtless for others, of the most serious concern for the efficiency of the organization. [7] 8 NEW YORK STATE MUSEUM REPORT Geology. In pursuance of the plan for the completion of the geological map of the State on the scale of 5 miles to 1 inch, areal surveys have proceeded over several quadrangles. In the Adirondacks region the Russell quadrangle has been cov- ered by Dr William J. Miller and a report rendered thereon. The survey of the Lake Bonaparte quadrangle has been completed by Dr A. F. Buddington. The work upon the survey of the Mount Marcy and Ausable quadrangles has been concluded by Prof. James F. Kemp, aided by Harold L. Alling. The survey and mapping of the West Point quadrangle undertaken especially as a means of facilitating instruction in geology at the United States Military Academy has been carried through by Dr Charles P. Berkey, super- intending the field work of Marion Rice. The report on the geology of the Gouverneur quadrangle by Prof. H. P. Cushing is completed. All the reports listed above are in condition for publication. Other geological activities have been a continuation of the ex- amination and surveys of the postglacial deposits and drainage by Dr James H. Stoller in the Saratoga region, Harold L. Alling in Essex county and John H. Cook in Albany county, while Prof. H. L. Fair- child has been engaged with the special problem of the evolution of -the upper Susquehanna valley, a work which it is hoped to extend to the entire course of the Susquehanna with the aid of the director of the Geological Survey of Pennsylvania. Researches upon problems relating to the mineral industry which have engaged attention have been connected with the origin and composition of the salt deposits of the State, a work which has entailed a large amount of analytical examination for the purpose of acquiring more exact information regarding the potash and other minor contents of these deposits. Much of this work has been executed by Mr Alling under the supervision of David H. New- land, Assistant State Geologist. A restudy has also been made of the iron ores of Orange and Putnam counties by R. J. Colony of Columbia University. Paleontology. In the category of special problems, Mr Hart- nagel has prosecuted further study of the Clinton formation and fauna in central and western New York, which has been productive of interesting results both in paleontology and stratigraphy. Doctor Ruedemann has advanced his investigations of the Lor- raine fauna of the Ordovician and has now completed a revision of the formation and fauna in which are substantial additions to the “TIRJOUIS *[ aN Iq Aq ydersojoyg [e109 jissoy e st osnjord oy} Ul UMOYS v[qqed AroAy “oeYS (UeIUOAD ePpPIP) UoYrueZZ FO do19jno ue Suissoss ‘oosyEO JO YRI0U SojIu € peq peor oy REPORT OF THE DIRECTOR IQIQ 9 ‘previous knowledge of the subject. It is hoped that it may be possible to publish this notable report in the near future. In previous reports reference has been made to progress on the monograph of the Devonian crinoids. This extensive undertaking which has been carried forward by W. Goldring, has been com- pleted. Its conclusion puts a period to an undertaking of long standing. My last report contained the results of the examination of the Bonaventure cherts made by Dr Rufus M. Bagg and the results have been of such interest that Doctor Bagg has been asked to prosecute an investigation of the Devonian cherts of the Onondaga limestone with the purpose of determining the microscopic life con- tained therein. Paleobotany. In all the history of paleontological investigation and collection in the State, fossil plants have been brought together quite incidentally to other investigations. Seldom has any special effort been made to search them out or to make a careful study of them. Notwithstanding, the Museum has by this desultory pro- cedure come into possession of a very extensive and variant collec- tion of the terrestrial plants of the Devonian period, a collection which has been authoritatively characterized as one of the largest assemblages known. Paleobotany is a phase of paleontology which has not received its share of attention in America and an under- standing of the first terrestrial floras of the world has been restricted to a very small circle of students. This is a condition which has prevented the entry of this knowledge into the understanding of intelligent men, all the more regrettable as it is the branch of knowl- edge which has had to do with the beginnings of the whole world of plant life. The paucity of this knowledge and the intelligent requirement for more of it have led the Geology Division of the National Research Council to establish a committee on paleobotany in accordance with the purposes of which, as suggested above, pro- vision has been made for a systematic pursuit of this field in this State. Several collectors are now in the field in search of this ma- terial and their efforts have thus far been attended with excellent results. A promising outcome of this work is indicated by the fol- lowing account of the rediscovery of the fossil “fern” trees of Gilboa in the upper Schoharie valley. The fossil trees of Schoharie county. A great autumn freshet in the upper valley of the Schoharie creek in 1869 tore out bridges, culverts and roadbeds around the little village of Gilboa and exposed in the bedrock of the hills a series of standing stumps of Io NEW YORK STATE MUSEUM trees. These stumps stood all on the same level in the rocks and their rootlets ran down into the original mud in which they had grown, now turned into a dark or greenish shale. All had been cut off by some ancient flood at about 3 feet above the base; some were large and some smaller, the largest having a diameter in the shaft of 2 feet or more with broad expanding root-base like a flat- tened turnip. Thus was brought to light the standing remains of the most ancient forest growth known in the geological records in any part of the world. Ten of these tree stumps were taken out from their ancient forest, all at the same level in the rocks, and most of them were brought to the State Museum, where they have — long constituted one of the remarkable exhibits of the vanished flora of the State. The effort made this year to relocate this primeval forest of the Devonian Period or to find some additional evidence of its extent. has proved successful. The old locality is deeply covered and the rocks of that level which carried these trees do not come to the sur- face again in the vicinity. But the work has been attended with unexpected results in finding the stumps of other trees of the same sort at a level 60 feet higher in the rock beds, giving evidence that the forest growth had reappeared in the same region at a later stage in Devonian history. The rediscovery of these primitive “ferns” is of very great inter- est from a scientific point of view. These trees are most nearly com- parable to the tree ferns of existing tropical forests but no botanist would be content with this comparison, as they have a frutificatioa quite unlike the spore-cases of the ferns, and the leaves were appar- ently narrow and straplike, branching simply and rarely and termi- nating in twin fruit cases. If the diameter of the trunks is carried upward in a tapering slope these trees must have reached a very considerable height of 20 to 30 feet, but it is possible that the trunks broke up not so far above their base into a shrubby or bushy cap. Their real nature is still a problem for the student of fossil plants. This will be disclosed in time but whatever the nature of this primi- tive forest growth may prove to be, they certainly afford an index to the geography of the western Catskills and the Schoharie valley during the late Devonian Period to which they belong. We have said that the tree stumps were found in places where they grew, that the shale under them are the muds in which they were rooted and that they are preserved at at least two levels in the rocks, one 60 feet above the other. Not far under the lowest forest the rocks carry true marine fossils. Tangled in the roots of the lower trees were found the remains of some brackish water animals. These facts of aod Ul SxUNI} 991} YM voOgTIy 1e paq ysar0j Jedd, aoejd UL SxUNI} 991} oy} JO UO FO JUSWOSIL[UA REPORT OF THE DIRECTOR IQIQ Il _ themselves show that the sea which covered this region slowly with- _ drew and the trees crept down from land to the water’s edge, or a grew over the delta plain of the fresh-water streams flowing in _ from the old land at the east. Then for a long time the first forest - must have been flooded by the waters, probably by the rising of the i sea which deposited the 60 feet of overlying rocks, until another _ retreat of the water again brought the forest down to the shore. _ There was an oscillation of the coast line, the sea rising and falling and the trees approaching, receding and approaching again toward _ the edge of the water. The story of the earth’s primitive forest when fully written promises to be an interesting one, and it is hoped to reproduce, in part at least, in the State Museum, this picture out of the dim past. It may be added to the foregoing “ story ” that these stumps when first found and recorded in the 18th report of the Museum, were studied by Sir William Dawson, then principal of McGill College and in his day the leading authority on the plants of the Devonian, and were regarded by him as probably “tree ferns,’ Psilophy - ton textilis, but present evidence indicates that they were also related to the cycad palms and probably are associated to the cycadofilices which were allies to both these groups. The location of the new series of stumps has been due to Herbert S. Woodward, who has had the assistance of Messrs Ruedemann and Hartnagel in the careful extraction of the remains and in the important discovery of the fruit cases. Archeology. Excavations on Boughton Hill. Late in the sum- mer of 1919 some field work was done on the historic Boughton Hill site in Ontario county. This site, which has been the scene of exca- vations and speculation on the part of antiquarians for more than a century, covers portions of the Green, Moore and McMahon farms in the town of Victor. The heart of the village seems to have been located on what is now a narrow strip 300 feet wide on the Moore farm. This strip was leased by the Museum and operations com- menced on September toth. It required but a few days of excava- tion to demonstrate that the site had been dug over for a period of many years and that but little remained for the systematic excavator to find. By persistent effort and by careful work twenty-five graves were discovered during a period of 30 days. The success of this search is due to the interest and conscientious labors of Everett R. Burmaster, who during a period of 15 years has acted as a field helper or as an advisor. The digging at Boughton Hill was difficult owing to the condition of the soil, which is a compact gravel- [2 NEW YORK STATE MUSEUM mixed clay. The difficulty was increased by the unsystematic — excavations of amateurs whose filled-up prospects constituted false — leads in many instances. The Moore farm is divided into two general sections, the agricul- tural plot on the top of the hill, and the pasture plot on the west slope. The portion excavated in the autumn of 1919 was the brow of the hill in the pasture plot. Here on two lobate ridges running out into the brook valley, were found the burials. The specimens recovered include one bone comb, four clay pipes, a woven pouch, two wooden spoons, several strings of wampum beads and shell runtees. European material included glass beads, brass kettles, brass arrow points, gun locks and barrels, knives, chisels and punches. Of considerable interest are the specimens of dried foods, further preserved from decay in the ground by impregnation with - copper salts derived from oxidation of brass kettles. These foods include apples, grapes, squash rind and seeds, pressed berries, corn bread and corn. Some tobacco leaf and “ fine cut” Virginia is also among the preserved vegetable substances. Through substances such as these it is possible to determine some of the foods used by the Indians who lived at Boughton Hill. The site is that known as Gandagora by the French. To the Indians it was Ga-on-sa-gaa-ah. This village was one of the great towns of the Seneca and was known to the colonists as early as 1637. During the conflict of the Iroquois with the French of Canada the village was attacked by Governor Denonville. With him were 1600 French soldiers, 800 of whom were trained men from France; the rest were hastily drilled habitants. To supple- ment this force there were some 1400 Indian allies, mostly Hurons and Ottawas. The Seneca occupants made several feeble efforts to defend their homes, but they were outnumbered ten to one. Fleeing before the superior invading force they abandoned and burned the village and fled to Gayaanduk, a fortified hill a half league to the west. This was almost immediately abandoned and burned, leay- ing the French and Indian invaders the task of destroying the corn fields and public storehouses. The French destroyed four prin- cipal villages of the Seneca and burned several small settlements, together with.their corn fields and garden plots. A few Seneca Indians were killed but the Ottawa allies of the French accused Denonville of killing more horses and pigs than Seneca enemies. “You have destroyed the nest,” said one Indian ally, “ but you have left the hornets with their stings.” ill. Antler spoon from a grave at Boughton H Excavated 1920. EPL Te amma? A (Cae i OZOI ‘JI UOWYsSnog je puNoyZ squiod JoyUe jo sodAT OZ-O161 ‘TI UOJYysSnog je soAvIs ur punoyZ squwoo s9}Uy » rg Antler combs found in graves at Boughton Hill, 1920 REPORT OF THE DIRECTOR IQIQ EB It was hoped that this important site might yield a large number of interesting remains that would shed light on the Denonville period of the Seneca. Our success during 1919 was sufficient to warrant — an additional examination during May 1920. Operations were started on May 15th, the entire tract of land on the Moore farm being post holed. For the first two weeks little was found, but as the work started on the east side of the hill at a point that must have been the old stockade line, burials were found in numbers. Nearly two each day were unearthed. In all in the thirty-three graves there were found about fifty skeletons. The burials at this spot differed considerably from those on the west side, in that there were many disassociated remains. This may be due to several causes ; first, the remains may be those of the slain after the battle; second, they may be the remnants of the house-burials; third, they may be the remains of those “ buried ” in trees and later taken down and thrown in burial pits. In the east burial site European artifacts were numerous, the usual iron axes, copper and brass kettles and iron knives occurring _ in about the same proportion as on the west side. The articles of _ native manufacture found here include one antler spoon with a forklike end, four complete bone combs and three combs with broken teeth. A number of triangular arrow points were recovered, these being exceedingly rare as surface finds since the inhabitants had used guns for a generation before the destruction of their vil- _ lage. Beads of many kinds were found. Where possible they were _ restrung bead for bead as taken from the burial. In this manner we have restored several of these necklaces to their original condi- tion. Of exceptional interest are the two pottery vessels found in graves. These were in a broken condition but it is hoped that they may be restored. Very few pottery fragments have been found on Boughton Hill and so far as we know none has been found in a com- plete condition, or even sets of restorable fragments. The type of pottery is a modified serrated or scalloped edge, of the Seneca or Neutral style of 1650. One pot has four perforated knobs that were _ evidently handles. The interesting history of Boughton Hill and the character of the recoveries will make our two expeditions the subject of a larger and more complete report. It should be noted now, however, that the site was secured through lease by favor of Mrs F. F. Thompson of Canandaigua, to whom the Museum is indebted for many gifts _ and favors. The field experts this year were George E, Stevens _ and David B. Cook, both of Albany. i4 NEW YORK STATE MUSEUM The Cornplanter Medal. The 1920 Cornplanter Medal was bestowed upon Mrs Mary Clark Thompson of Canandaigua in recognition of her numerous services in connection with movements 1elated to archeology, ethnology and history. The medal was — received for Mrs Thompson by the Director of the State Museum, who made an appropriate address. The ceremonies of presentation are held under the auspices of the Cayuga County Historical Society of Auburn. The medal is given for notable services to the science of anthropology, to philanthropists who have given great benefits to the Iroquois, the historians, writers and artists, all of whom must have contributed to the knowledge or welfare of the Iroquois. Up to the present time three other persons associated with the State Museum have received the medal, Williara M. Beauchamp, Arthur C. Parker, Alvin H. Dewey. The New York State Archeological Association. This organ- ization, started four years ago, is flourishing and growing in numbers and enthusiasm. Its publications are popular and have had a con- siderable circulation. At present there are three organized chapters, one at Cooperstown, one at Rochester and one at Schenectady. The Rochester chapter has more than 250 members and gives a regular course of lectures, generally ten in number each season. Its annual banquets provide the means for a gathering of archeologists from all parts of the State. At the February 1920 meeting, Mr Langdon Gibson, president of the Mohawk Valley chapter, Schenectady, gave the principal address on “ Tramping the Arctics with the Eskimo,” A new chapter is under way in Syracuse and only awaits installation. It has been suggested that this chapter be named after William M. Beauchamp LL. D., the. dean of archeologists in this State. Activities of the New York State Indian Commission. At the beginning of this fiscal year the State Legislature created the New York State Indian Commission to be composed of members of the Legislature and certain representatives of state departments. The Governor selected the Archeologist of the Museum as the repre- sentative of the Education Department and at the organization meet- ing of the commission the Archeologist was elected secretary. [a this way there has been no uncertain recognition of the ability of the State Museum to supply information relative to the Indian inhabitants of the State. The commission has as its duty the study of the status of the New York tribal Indians and a subsequent conference with the commit- tees of Congress relative to that statute. There is an apparent con- REPORT OF THE DIRECTOR IQI9 15 flict of jurisdiction between the state and federal governments respecting Indian affairs. Beyond this the Indian tribes claim a cer- tain independence and have asserted the right to regulate their own internal affairs. Certainly the Empire State can well afford to make a thorough study of this situation and provide the needed relief to ihese nations once so powerful as to be courted by the foreign powers that sought to colonize America. The Indians chiefly affected by this commission are the Onondaga nation, near Syracuse; the Oneida tribe near Oneida; the St Regis Mohawks in Franklin county; the Tonawanda Seneca Band in Genesee and Erie counties, near Akron; the Tuscarora tribe, near Lewiston, Niagara county; the Seneca Nation on two reservations, one near Gowanda and one near Salamanca. Each tribe has a somewhat different status but all are regarded as wards of the federal government and all fall under the provisions of the Pickering treaty of 1794-95. This treaty pledges the Indians immunity from disturbance and interference in the possession of their lands. While the Indians are regarded as “ wards” we have not been told when they became wards or how, for when the treaties were drawn these Indians were regarded as competent con- tracting parties. Somewhat later they were denominated wards. If they are wards of the federal government the question arises as to what: right the State has to legislate for them and how it can force the Indians on their several reservations to obey state law. The government has been disposed to let the State care for the Indians in the matter of schools, highways, enforcing the sanitary code, and in cases of the poor and indigent. There is now some question as to the right of the State to do this, though the moral propriety of the fact is not impeached. The Indian Commission is charged with the task of bringing about a well-understood status and in eliminating the causes of dissatisfaction and the barriers to progress. If the Museum through its department of archeology can be of assistance in clearing up this vexatious problem that has troubled the adminis- _ tration of Indian affairs in this State for so many years it will be felt that a practical good has been accomplished. The members of this Commission are Assemblyman E. A. Everett, chairman; Senator Loring F. Black, vice chairman; Speaker Thad- deus C. Sweet, J. Henry Walters, De Hart H. Ames, Attorney Gen- eral Charles D. Newton, Charles D. Donahue, Peter McArdle, Dr Robert W. Hill, Dr Matthias Nicholl jr, Chief David R. Hill, Arthur C. Parker, secretary. 16 NEW YORK STATE MUSEUM New York Indian Welfare Society. During the month of May a general call was issued to the Indians of this State and their friends calling them into a general conference for the purpose oi discussing their present and future needs. The meeting was held May 11th in the Historical Society Building in Syracuse and on the 12th at the Onondaga Council House. For the first time in many years Indians of all classes and schools of thought met in joint con- ference. The temporary chairman was Jesse Lyon, the courier of the Six Nations. Mr Lyon is a stalwart exponent of the old régime and is bitterly opposed to citizenship, preferring the citizenship of his tribe to that of the United States. After a vigorous session in which each division explained its beliefs, an election was held. The officers selected are: A. C. Parker, president; Dr Louis Bruce, a St Regis Mohawk, treasurer ; David Hill, an Onondaga, secretary. The vice presidents are: George Thomas, Onondaga; Nicodemus Billy, Tonawanda; Alexander Burning, Oneida; Delos Kettle, Seneca. The councilors are: Jesse Lyon, Onondaga; Moses White, St Regis; Howard Gansworth, Tuscarora; Rolling Thunders, St Regis. There is also an advisory board composed of two sections ; the section of the last conference and the section of the future con- ference. Dr William M. Beauchamp is chairman of the Syracuse section and Alvin H. Dewey, chairman of the Rochester section. The Rochester meeting will be held November 11, 1920 under the auspices of Morgan chapter of the New York State Archeological Association. This organization was conceived by Dr Earl E. Bates of Syracuse, who is the honorary president. At the Syracuse meeting in May there were present representa- tives of the State Indian Commission, including Chairman E. A. Everett, David R. Hill and Dr Robert W. Hill. The Friends Indian School of Tunesassa was represented by William A. Rhoads, superintendent, and Henry Leeds, missionary. Wild Flowers. The “ Wild Flowers of New York” has been completed and published. This quarto work in two volumes has engaged the attention of the State Botanist for five years and has been progressed and brought to conclusion in spite of great dif- ficulties growing out of the war and its consequences. The beauty of the execution of this work is greatly to the credit of all who have had a part in its making and it is confidently believed that it will render an excellent service in disseminating a knowledge of the native flora of the State. . Living Mollusca. For many years as time has permitted, there has been in preparation an illustrated report on the Mollusca of the Delos Big Kettle (Sai-no-wa), a Seneca chief, and the Rev. William M. Beauchamp (aged 92), for many years author of and contributor to State Museum bulletins on Indian subjects. REPORT OF THE DIRECTOR IQIQ 17 State by Dr Henry A. Pilsbry of the Philadelphia Academy of _ Natural Sciences, the recognized leading authority in this field. This _ work is now practically complete and it will be offered for publica- . _ tion in the hope of reviving among our people the interest in the “Delle science ” which was so keenly alive a half century ago. BOTANY The work of the State Botanist’s office during the year ending _ July 1, 1920, has been largely a continuation of lines of investigation and routine previously reported upon. Field investigations. During the latter part of the season of 1919 there was carried on a continuation of botanical field work in the lake region of central New York, particularly about Oneida lake, and the region immediately to the east of that body of water. _ Several species of plants and fungi previously unknown to that region were found and added to the state herbarium. Particular attention was given to those fungi known as plant rusts. A few days during May 1920 were also spent in the same region, _ resulting in additional knowledge regarding the early spring vegeta- tion of that region. In late June, four days were spent at Lake Bonaparte, northern _ Lewis county, supplementing field work during early June of 1919, at the same place. The results of these field investigations will appear in the reports of the State Botanist for 1919 and 1920. Ferns and flowering plants of New York State. A complete list of the ferns and flowering plants of this State which has been ia _ course of preparation for some time has nearly reached completion. _ This list gives the scientific and popular name of every species known _ to occur within the boundaries of the State, the comparative abund- ance of each one, and in case of those species which are rare, local or very uncommon, the previously published notices of them are cited, and definite reference to authentically determined specimens : in the leading herbaria are added. Similar lists have been published ; upon the flora of New Jersey, Connecticut and other states and have fulfilled a long felt demand upon the part of those interested in the _ vegetation of these states, both from a popular and from a scientific a point of view. _ Determinations. During the six months ending July 1, 1920, the ' State Botanist’s office has been called upon to determine 165 speci- mens of plants (including fungi and ferns). These determinations were made for 47 persons, only six of which were from outside the ee 18 NEW YORK STATE MUSEUM State herbarium. Continued curatorial work on the collections has resulted in bringing the large assemblage of fungi, mosses, lichens, ferns and flowering plants into an improved systematic — arrangement. . In addition to assembling the current collections for incorporation into the herbarium, a large amount. of unmounted material has been brought together and is in process of being mounted by competent temporary assistance, beginning June 15, 1920. ENTOMOLOGY The Entomologist reports that the season of 1919 was made note- worthy in entomological annals by the discovery in late January of the European corn borer at Scotia, Schenectady county. The infestation was found subsequently to include portions of Albany, Schenectady, Schoharie, Montgomery, Fulton, Saratoga and Rens- selaer counties, and to extend from a little east of Troy westward to Fort Hunter, north nearly to Saratoga and south to Esperance. The presence of the pest on the Mohawk flats made the problem more serious because there was constant danger of high water with the accompanying drifting of corn stalks, some presumably contain- ing living caterpillars, down the river. The situation was carefully studied in early February and after a series of conferences with state and federal authorities, it was decided to make an attempt to clean up the infestation and prevent the further spread of the pest. The entomologists of the State were unanimous in adopting a progressive policy and as an outcome of their representations the Legislature passed an emergency act appropriating $75,000 to the State Department of Farms and Markets to be used for corn borer control. Although the time for doing effective work was very limited, and conditions in early spring decidedly unfavorable for effective operations, the undertaking resulted in a very satisfactory clean-up of the known infested terri- tory, which at that time approximated 300 square miles. ‘There was then no good ground for believing there would be but one genera- tion of the insect in New York State and that consequently local injury would be comparatively slight because there is only a small- variation in climatic conditions between the infested section about Boston, Mass., where two broods are the rule, and the territory where this insect was found in eastern New York. This peculiar restriction could not be demonstrated until mid-September conditions indicated that the borers had ceased activities for the season. Se ae REPORT OF THE DIRECTOR I9QIQ 19 Another infestation was discovered at North Collins, Erie county, in early September 1919, and as a result of scouting by both federal | and state men the infested area in that section has been found to approximate 400 square miles and to include portions of Cat- _taraugus, Chautauqua and Erie counties. _ The situation was of more than usual interest since in early spring it was impossible to get more than a tentative identificatioa _ because Pyraustid larvae, a group to which the European corn borer belongs, are so similar that at the time no unquestioned recognition characters were known. ‘The situation was further complicated by the fact that a very similar borer occurs rather commonly in smartweed and while this latter is of no economic importance, it occasionally bores in corn stalks and it was therefore necessary 10 distinguish between this harmless native species and the much more dangerous European introduction, if state money was not to be wasted in cleaning up areas outside the infested territory. The Entomologist addressed himself to the early solution of this problem and after securing series of specimens from different sections of New York State and from other parts of the country, worked out differentiating characters which have been largely sustained by later investigations. _ Conditions were such in the spring of 1919 that it was very desir- able to ascertain at the earliest possible moment the distribution of _ the European corn borer in the State, consequently bulletins, posters and circulars were widely distributed. The Entomologist prepared a brief circular letter which was sent very generally to schools of the State, Cornell University Extension Bulletin 31, of which an _ edition of 40,000 was printed, and the Education Department’s Bul- _ letin to the Schools of June Ist, the last illustrated by four admirably executed colored plates. Numerous press notices were also sent out. The Department of Farms and Markets published Circular _ No. 182 and issued a number of quarantine orders. The result of these publicity and regulatory measures was an extraordinary inter- _ est in all manner of corn insects and as an indirect outcome valuable information was secured concerning a number of comparatively _ unimportant pests, notably the lined corn borer and grass webworms. The European corn borer is of such general importance and its _habits in New York State so different from those in Massachusetts _ that application was made to the Legislature for a special appropria- _ tion for the investigation of the status of this insect and $5000 was _ appropriated. This money is being used in a careful field study of : the pest to ascertain the rapidity of spread, the amount of injury 20 NEW YORK STATE MUSEUM and the possibilities of control or repressive measures. The work has been placed in charge of D. B. Young, who was temporarily detailed from the Entomologist’s office. Hall B. Carpenter of Somerville, Mass., was also engaged as a special assistant for this work. Data in regard to a large number of fields have already been secured and much material collected which will be duly classified at the close of the active season. Results so far obtained clearly indi- cate a considerable difference in habits in New York State as com- pared with the infested areas of Massachusetts. These variations are of much practical importance because of their bearing upon quarantine restrictions or other methods designed to prevent further spread. A detailed report upon this work can not be completed for some months. Early in July 1919, the Entomologist was appointed collaborator of the Bureau of Entomology, United States Department of Agii- culture, and specifically authorized to investigate corn borer control in the states of New York and Massachusetts. He was also appointed chairman of a subcommittee on the European corn borer, subsequently changed to a subcommittee on insect control, of the committee on policy of the American Association of Economic Entomologists and a member of a special committee appointed at the Albany-Boston conference on the European corn borer. He has in these various activities been able to exercise a marked influence upon both state and national phases of the situation. He has felt compelled to do this because the insect is one of national importance and measures adopted in one commonwealth must be contingent to a greater or less extent on those enforced in other states or pressed to a successful conclusion by the representatives of the federal Bureau of Entomology. A detailed account of the investigations and activities in relation to this recently introduced pest may be found in the Entomologist’s report. Other corn insects. The great interest in the European corn borer caused most careful and repeated examinations of corn throughout the State and one outcome was the finding and reporting of a number of injurious species. The lined corn borer, hitherto supposed to be rare in New York State, was found to be rather widely distributed and frequently injuring a considerable proportion of the corn on recently turned sod. The well-known stalk borer, a generally recognized pest in a variety of thick-stemmed plants, caused numerous complaints, though in most cases the injury was by the corn ear worm. This last was in not a few cases thought to be the European corn borer. REPORT OF THE DIRECTOR IQIQ 21 4 : - Several less-known corn insects were also brought to the attention of the Entomologist. The material received during the past season has made possible a _ more accurate appraisal of the economic status of these differenti _ forms and in order to facilitate their recognition a popular key giv- ing the more conspicuous characters was prepared and generally distributed as a special folder. Additional details regarding the work of the different species may be found in the Entomologist’s _ report. _ §$mall grain pests. Studies of the wheat midge, Thecodip- losis mosellana Gehin., begun in 1919, were continued the é past season and much additional information secured concerning the - economic status of the pest. It was found to be generally present | in the rye fields of the eastern part of the State and in wheat fields in the western area. It was particularly abundant in portions of _ Genesee, Monroe, Niagara and Wayne counties, the indicated reduc- _ tion ranging from 17 to 27 per cent with very little crop injury _ from wheat scab or loose smut. The data show close correlation _ between the abundance of maggots and the number of shrunken 5 _ blasted grains of wheat and rye. The evidence at hand indicates a _ presumably much greater loss from wheat midge infestation than has _ hitherto been suspected. A detailed discussion of the data is given ‘ in the Entomologist’s report. The collation of similar data for _ 1920 is in progress. q fine vElessiam fly, Phytophasa destru¢ tor. Say is _ one of the most destructive and best known wheat pests. Through ‘ the courtesy of Prof. C. R. Crosby of Cornell University and W. R. i McConnell of the United States Bureau of Entomology, the Ento- " -mologist has been able to include in his report summarized data " concerning the abundance of this insect in the State for the years 1917 to 1919 inclusive. It will be seen by reference to the discus- : sion in the body of the report that there has been an increase in the “Wayne counties. These data are of value since they indicate tend- encies in different parts of the State and can be used advantageously in designating areas where stricter adherence to precautionary _ measures is advisable. _ Wheat joint worms, Isosoma tritici FitchandI.vagi- -nicolum Doane, occur throughout the State and as in the case of the Hessian fly, data have been included concerning the abun- _ dance of these two insects for the years 1918 and 1919. Reference 22 NEW YORK STATE MUSEUM to the summary in the report of the Entomologist shows a decrease the past season in the abundance of both joint worms, this being particularly marked in Genesee and Schuyler counties with a tendency in the opposite direction in the case of Ontario anid Orleans counties. Observations upon the army worm, Heliophila uni- puncta Haw., show that the partly grown caterpillars survived the very severe winter of 1918-19 in Saratoga county, they being repeatedly found in partly rotted corn stalks, and in smaller num- bers in the spring of 1920. These are new records for this sectioa of the county and have an important bearing upon army worm out- breaks. A distinctly unusual feature was the submission of leather jackets or maggots of a crane fly, Pedecia albivitta Walk. accompanied by the statement that they occurred in large numbers in Schuyler county in an oat field and were presumably causing some injury. Other field crops. The ordinary crop pests attracted compara- tively little attention, though in early spring there was considerable complaint of an unusual abundance of asparagus beetles, Crio- ceris asparagi Linn. These insects were specially trouble- some upon commercial beds, not only because of their feeding upon the shoots, but on account of the numerous black eggs which neces- sitated very careful washing before the asparagus was taken to market. — There was a distinctly unusual outbreak of the green clover worm, Plathupena scabra Fab., upon beans, the greenish white-striped caterpillars feeding generally upon the leaves of both common and lima beans and causing serious and somewhat general injury in various parts of the State. Codling moth. Field studies of the codling moth have been con- tinued in cooperation with the bureau of horticulture of the State Department of Farms and Markets. Special attention was given securing exact records of evening temperatures as well as the maxima and minima. The accuracy of this work was materially increased by the cooperation of the United States Weather Bureau in loaning thermographs and supervising the setting up of the instru- ments. The intimate relations existing between evening tempera- tures and codling moth oviposition are graphically represented in a chart prepared by L. F. Strickland, who was also responsible for the observations upon egg deposition in various orchards. The demon- stration of this relationship is a material step in solving the vexatious problem of codling moth control in the western part of the State. REPORT OF THE DIRECTOR I9QI9Q 23 The series of experiments to determine the relative efficiency of the several sprays for control of the codling moth in the westera part of the State have been continued. The most marked results, as . were to be expected, were obtained from the first or calyx application and while the reduction in wormy apples was decidedly less in the case of the second and third treatments, there was no question but that these additional sprays are amply justified by other considera- tions. Tests of the value of nicotine in the spray applied about three weeks after blooming, indicate little benefit in the destruction of adult codling moths or recently deposited eggs and so far as this insect is concerned, the inclusion of this costly insecticide in the second application can not be advised though it is undoubtedly very beneficial when aphids are numerous. The data in relation to this insect secured the past season are discussed in some detail in the body of the report. Shade tree insects. The past season was marked by the dis- covery of another pest in the United States upon which has been tentatively bestowed the common name of elm ribbed cocoon-maker. It is with very little question the European Bucculatrix ulmella Zell. It has been reported as seriously injuring European elms in the Rochester parks. A recently introduced willow leaf beetle, Plagiodera versicolora Laich., was brought to notice the past season on account of the serious injury to weeping willow foliage in New York City. It is also known as a pest of poplar and may possibly be of some service in checking the indiscriminate planting of this somewhat undesirable shade tree. m@he elm leat beetle, Galerneella Yue elo la Mull was somewhat injurious here and there in the State, particularly outside of areas where it was very destructive 10 to 15 years earlier. This is probably due in part to better control in localities where the insect has caused the most damage and partly to the somewhat unfavorable climatic conditions of recent years. The bronze birch borer, Agrilus anxius Gory, continues its nefarious work and here and there throughout the State many magnificent birches are succumbing to the work of this borer. It is only a question of time before all the cut-leaved birches will suc- cumb unless they are systematically protected. A compilation of the office records of the last twenty years indi- cate a probable biennial life cycle for the large, strikingly colored Say’s blister beetle. Pomphopoea sayi Lec. This insect 24 NEW YORK STATE MUSEUM is numerous approximately every other year when it attracts atten- tion on account of its feeding in swarms upon the blossoms of vari- ous trees, particularly honey locust. Forest insects. The destructive work in recent years of the hickory * bark beetle;') E'¢:co'ptogaster q Wad pws ome nosa Say, has resulted in bringing to attention a number of insects of secondary importance. Notes upon these latter have been com- piled and are placed on record in a summarized form in the Entomologist’s report. There was an outbreak of the antlered maple caterpillar, Heterocampa guttivitta Walk, in Chautauqua county, accompanied by defoliation of sugar bush in areas where the insects were most abundant. The interesting maple leaf cutter, Paraclemensia acorifoliella Clem.,, again attracted notice on account of its unusual abundance in the vicinity of Lake George. Lectures. The Entomologist has delivered a number of lectures or participated in discussions on insects, mostly economic species, before various agricultural and horticultural gatherings, some of these being in cooperation with farmers institutes or county farm bureau agents; a considerable proportion, owing to the conditions prevailing during the past year, have related to the European cora borer and its control. Some of the more important were before a subcommittee of the United States Senate at Washington, a special meeting of the Council of Farms and Markets at Ithaca, a special conference of state commissioners of agriculture and official entomologists at Albany, the annual meetings of state commissioners of agriculture at Chicago and the American Association of Economic Entomologists at St Louis. Gall midges. The 33d report of this office, issued during the period covered by this report, contains part 6 of the study of gall midges, a portion devoted to many very interesting and highly com- plex members of the tribe Itonididinariae, one of the common repre- sentatives being the pear midge. The Key to the Sub-families, Tribes and Genera of the Itonididae or Gall Midges of the World, which appeared in the Philippine Journal of Science during the present year, is the most comprehensive paper of this character which has yet appeared. Gall insects. The “Key to American Insect Galls” was pub- lished during the past year. It is the only comprehensive tabulation of these interesting deformities in America and since it deals pri- marily with the more obvious swellings or plant malformations REPORT OF THE DIRECTOR IQIQ 25 } rather than with the minute and highly complex gall makers them- selves, it will greatly facilitate the study of the interrelations be- tween plants and insects. Owing to the great demand for this bulletin, the edition was rapidly exhausted. Publications. A number of brief popular accounts relating to the | more important insect pests have been prepared as heretofore and _ widely circulated through the county farm bureaus, local papers and the schools. : The Report for 1917 did not appear until the current year and it and the Key to American Insect Galls, mentioned above, are the two Museum bulletins on entomology which were issued during the _ year. The publications relating to the European corn borer and to _ gall midges have been mentioned above. Collections. Very desirable additions to the state entomological collections have been made during the year, some of the best material _ being reared in connection with studies of insect outbreaks or as a result of requests for information concerning previously unknown forms. Special attention has been paid to the acquisition and preser- | vation of immature stages, since these are very difficult to secure. _ This is particularly true of a number of borers similar to the _ European corn borer found in the stems of various plants. The special work upon the European corn borer is resulting in numerous additions to the state collections. Henry Dietrich, now of Berkeley, Cal., most generously donated to the Museum 551 specimens of Coleoptera, representing 160 species, 55 of these being new to the state collections. D. B. Young, assistant entomologist, donated from his personal collections of earlier years, a large series of Coleoptera, consisting of 648 specimens belonging to 369 species previously unrepresented in the state collections. This large addition to the collections has necessitated the rearranging of most of the Coleoptera and in addi- _ tion it involved the study and identification of numerous obscure species. This work has been prosecuted in addition to numerous _ identifications for correspondents and other routine duties. Miss Hartman’s time has been very fully occupied in addition iv the usual duties of the assistant, by the many translations of techni- cal literature needed in systematic work, the making of numerous excellent microscopic preparations of small insects and the arrange- _ ment and care of the pressed specimens of insect work and the exten- _ sive accumulations of alcoholic material. The many additional calls upon the staff incident to the work upon the European corn borer has greatly restricted the amount of time 26 NEW YORK STATE MUSEUM which could be given to the identification and arrangement of collec- tions, though some progress has been made along these lines. The special work upon European corn borer authorized by the last Legislature necessitated the temporary transfer of Mr Young to ‘take charge of the work and the appointment of W. H. Hoffman to fill the temporary vacancy. Hall B. Carpenter has been appointed special assistant in corn borer work. It is impossible, as pointed out in the previous report, to build up the state collections in a satisfactory manner without more funds and assistance, since work of this character is very exacting and time- consuming. Horticultural inspection. The nursery inspection work of the bureau of plant industry, State Department of Farms and Markets, has resulted as in former years in a number of specimens represent- ing various stages of insect development, some in very poor condi- tion, being submitted to this office for identification. The need of accurately identifying borers in weeds and corn found in connection with European corn borer operations of last summer has resulted in the Entomologist giving much time to the study of boring caterpillars for the purpose of distinguishing between the destructive and comparatively innocuous forms. This was very important since the boundaries of the infested territory were neces- sarily determined by the identifications of all such material. General. The work of the office has been materially aided as in past years by the identification of a number of species through the courtesy of Dr L. O. Howard, chief of the Bureau of Entomology, United States Department of Agriculture, and his associates. There has been very effective and close cooperation with the State Depart- ment of Farms and Markets, particularly the bureau of plant indus- try, the county farm bureau, the State Experiment Station and vari- ous public welfare organizations. A number of correspondents have donated material and rendered valuable service by transmitting local data respecting various insects and assisting in other ways. It is a pleasure to record that there has been, as in the past, a most helpful cooperation on the part of all interested in the work of the office. ZOOLOGY The attention of the Zoologist, in the line of investigation, has con- tinued to be directed to the study of the extensive Araneid fauna of the State. Supplementing the general account of the spiders of New York but preliminary to it, a revision of the family Pisauridae has been undertaken and is nearing completion. REPORT OF THE DIRECTOR IQIQ 27 Localities selected for field work have included regions of diverse topography in Orange, Ulster and Dutchess counties, and collec- tions of considerable extent have been brought together. Concern-. ing these it is proposed to prepare a separate report. The report on the molluscan fauna of the State which has received the particular attention of Dr H. A. Pilsbry of the Philadelphia Academy, is now ready for the printer. Doctor Pilsbry’s account is monographic in extent and illustrated with many beautiful plates ‘executed in color and in black and white by Helen Winchester. Dr Roy Miner, of the staff of the American Museum, whose researches on the myriapods of the State were interrupted by war activities, reports considerable progress in the preparation of his memoir. New groups. The limitations of space in Zoology Hall prohibits the addition of many large habitat groups without a general rear- rangement of the existing cases; but small groups of skunks and opossums designed to occupy limited floor space have been installed and other groups are in the course of preparation. Through the interest and cooperation of the Conservation Com- mission, the State Museum has received by legislative appropria- tion, $1500 which will materially increase the collection of fishes from the fresh waters of the State. The proper care and arrangement of the lesser invertebrates which are usually preserved in alcohol has always been of great concern to the museum curator. With the idea of making such specimens readily accessible and at the same time conserve storage space, a system of suspending small vials on vertical wire screens has been adopted. The supporting screens are filed in specially constructed cases of uniform size but adapted to receive vials of varying dimen- sions. By this method the handling of individual specimens ox groups of specimens is facilitated, and the flexibility of the scheme permits indefinite expansion. Beneath the vertical files, drawer spaces provide room for larger jars of specimens and _ biological material. Accessions. Benjamin W. Arnold of Albany, whose extensive collection of birds’ eggs was presented to the Museum in 1917, has added an important series of specimens from the Falkland islands. The Henry A. Slack collection of birds’ nests and eggs from the vicinity of Albany has recently been acquired through the courtesy of Miss E. Cary. The Museum has also purchased the skull of the extinct great auk to supplement the Shufeldt collection of avian skeletons already in its possession. 28 NEW YORK STATE MUSEUM As an example of the persistence of certain large mammals in occupying, or perhaps reoccupying, well-settled territory, may be cited the capture of a Canada lynx in March 1920 by Isaiah Kilmer at Jackson’s Corners, N. Y. The skull has been added to the col- lections. Fragments of the remains of a fossil elephant (mammoth) con- sisting of skin, muscular tissue, adipocere and hair of varying lengths and texture from Alaska, were the gift of Langdon Gibson of Schenectady. Considerable interest is attached to these speci- mens because of their identity with the remains of the mammoth found within the limits of New York and because of their extraor- dinary preservation. ARCHEOLOGY AND ETHNOLOGY The work of the division of archeology and ethnology as has been explained in previous reports, covers several fields of activity and includes both field and office research. Beyond this, the nature of our subjects, touching human needs of the present day, places us in demand by several regular and some special branches of state service. Archeology and ethnology deal with the records of human activity, customs, material culture and social organization. Our Indian population with which we are especially concerned, still — lingers with us and while constituting an interesting memorial of the past, also presents evidence of the virility and vitality of the Iroquois people. -To some extent the existence of separate political units within the body politic creates special problems. Our endeavors thus reach from the most remote antiquity of the red race in this State to the newest of Indian babes. The office routine of the year has consisted of the work of cata- loging, making of labels, preparing of specimens for exhibition, study of records and the caring for requests by numerous correspondents. The fiscal year 1919-20 has brought an unusually large correspond- ence, indicating in no uncertain measure the value of this division of the Museum to the public and to the specialist. Our catalog of archeological specimens is nearly complete and includes a serial catalog of all specimens acquired since 1911 and a cross check catalog by subjects. The subject catalog is of special value in determining the relative number of each specimen or class of specimens. The patient work of Howard Lansing, who died two years ago from an injury sustained while in the performance of his duties, has been continued by Harry C. Wardell, the preparator of the Museum. 7 REPORT OF THE DIRECTOR IQIQ 29 The collections installed in the various cases have been cared for and certain special exhibits installed. These vary from time to time, as opportunity affords, in order to create public interest. Dur- ing the winter and spring months the newspapers of Albany, espe- cially the Times-Union, through the interest of Hon. Martin H. Glynn, have published extended accounts of these exhibits. This publicity swelled the crowds of visitors, especially those who came during the period of the Sunday openings. The large numbers of visitors and the appreciation manifested have served to stimulate up-to-date exhibitions and special displays. The most recent large collection installed is that made by Alvin H. Dewey, Esq., of Rochester. This collection, described in the report of 1918-19, has been placed in the west room of Ethnology Hall. Special cases were made for it and both because of the class of material and the method of exhibition, the collection has attracted much interest and comment. Public interest. There is a keen public interest in this section of the Museum as evidenced by the numerous visitors that come to our halls. We have sought to cater to the intelligence of the citizen who has not had the advantage of a special technical.training in archeology and, at the same time, we have sought to make our exhibits instructive. The large number of letters received asking for information and assistance in various lines with which our sub- jects concern indicates that we are influencing an increasing field. Many visitors come to the office and give valuable information con- cerning sites and their location, and others bring or send specimens as donations to our collections. In this connection it is interesting to note that at least 500 col- lectors of Indian relics and students of American Indian history and ethnology, within the State of New York, look to this section for information and guidance. Our bulletins are in constant demand _ and many of them have been entirely exhausted, pointing out the need of larger editions for future publications. STAFF OF THE DEPARTMENT OF SCIENCE The members of the staff, permanent and temporary, of the _ Department as at present constituted are: ADMINISTRATION John M. Clarke, Director Jacob Van Deloo, Secretary and Director’s Clerk Anna M. Tolhurst, Stenographer 30 NEW YORK STATE MUSEUM GEOLOGY AND PALEONTOLOGY John M. Clarke, State Geologist and Paleontologist David H. Newland, Assistant State Geologist, Curator of Geology _ Rudolf Ruedemann, Assistant State Paleontologist, Curator of Paleontology William L. Bryant, Honorary Custodian of Fossil Fishes C. A. Hartnagel, Assistant in Geology, Curator of Stratigraphy Winifred Goldring, Assistant in Paleontology Charles K. Cabeen, Mineralogist Esther K. Bender, Draftsman Noah T. Clarke, Technical Assistant H. C. Wardell, Preparator Edith A. Lipschutz, Stenographer Charles P. Heidenrich, General Mechanic Stephen D. McEntee, Clerk John L. Casey, Custodian of Museum Collections William Rausch, Cabinet Maker Jerry Hayes, Laborer Edward Noxon, Laborer Temporary Experts Areal Geology Prof. H. P. Cushing, Adelbert College Prof. W. J. Miller, Smith College Prof. G. H. Hudson, Plattsburg State Normal School Prof. W. O. Crosby, Massachusetts Institute of Technology Prof. George H. Chadwick, University of Rochester Prof. Charles P. Berkey, Columbia University Prof. A. F. Buddington, Geophysical Laboratory, Washington Marion Rice, Columbia University Economic Geology Harold L. Alling, Columbia University R. J. Colony, Columbia University Geographic Geology Prof. Herman L. Fairchild, University of Rochester James H. Stoller, Union College John H. Cook, Albany | REPORT OF THE DIRECTOR I9QIQ Suu Paleontology Dr Rufus M. Bagg, Lawrence College Florrie Holzwasser, Columbia University Vincent L. Ayers, School of Mines, State College, Pa. Herbert P. Woodward, University of Rochester Joseph Bylancik, Albany BOTANY Homer D. House, State Botanist Temporary Expert Helen La Force, Schenectady ENTOMOLOGY Ephraim P. Felt, State Entomologist D. B. Young, Assistant State Entomologist Fanny T. Hartman, Assistant to Entomologist Helen L. Ryan, Stenographer Matthew J. McGarry, Page Temporary Experts Hall C. Carpenter, Massachusetts Agricultural College William A. Hoffman, Cornell University ZOOLOGY Sherman C. Bishop, Zoologist Benjamin Walworth Arnold, Honorary Curator of Ornithology Arthur Paladin, Taxidermist Temporary Experts Dr H. A. Pilsbry, Philadelphia Roy W. Miner, New York ARCHEOLOGY Arthur C. Parker, Archeologist Temporary Experts Everett R. Burmaster, Irving William B. Moore, Victor David Cook, Albany George Stevens, Albany 32 NEW YORK STATE MUSEUM ACCESSIONS TOMWHE COLLECTIONS GEOLOGY Donation Luther, D. D., Naples Slabs showing mud-flows and beach markings from Naples, N. Y.. Finley, Dr John H., Albany Photograph of moon, at last quarter, taken September 15, 1917, at Mount Wilson Observatory Direct photograph of sun taken August 12, 1917, at Mount Wilson Observatory, showing distribution of sun spots. Spectroheliogram of the sun showing its greatly disturbed surface. Taken at Mount Wilson Observatory August 12, 1917 Gould, Rev. E. W., Bristol, Vt. Slab of Canajoharie shale showing glacial scratches from shore of Lake Champlain. at ‘Panton, Vt...... .. S004... aoe Collection Newland, D. H. & Alling, H. L. Rock salt and brines from western New York..............-..- Newland, D. H., Albany Iron ores of southeastern New York, magnetites, limonites and CATDONALEES.. ois. 5 cieiedicteaitn thats t austere toe wer eta ee soccer Feldspar from Gailor quarry, Saratoga Springs............+....- White quartz, Gailor quarry, Saratoga Springs.................6: Strontianite from Brayman shale, Schoharie, N. Y............... Pyrite from Brayman. shale, Schoharie,;\N..Y.........scseu eee Colony, R. J., Columbia University Quartz and quartzites from various New York localities........ Alling, H. L., Rochester Graphite from the “Adirondacks. 045.0%... osc oss be 4 cee ee Hartnagel, C. A., Albany Dark gray oolite ore with the spherules of chamosite. From thin band 1 foot below main oolitic iron ore at Clinton, N. Y....... PALEONTOLOGY Donation Bryant, William L., Honorary Curator of Fishes, Buffalo 6 25 25 25 From Conodont bed (Genesee shale) eighteen-mile creek, Erie county: Specimen with teeth of Dittodus priscus Eastman............... Ptyctodus compressus Hastidaiey. eveyne eee vk. ss cicis) os eter ee Dittodus minimus Huss &) Bigvants. 0 ae cite iccie ae eee Dinichthys magnificus H. & B. (Fragment of suborbital plate).. Arthrodisé or, Stenognathus: (plate). 0.00). sfc. see eee Dinichthys newberryi Clark (marginal plate)............0+.0000+ en | a REPORT OF THE DIRECTOR I9I9 Bryant, William L.— continued Machaeracanthus peracutus Newberry. Fragment of spine...... Dinomylostoma buffaloensis H. & B. Functional portion of mandi- LDL MRI eMac U Soe Aa STU UNG Mee ater ete cae wits cata dg dict at erates eee Ptyctodus calceolus Newberry. Imperfect dental plates.......... Ptyctodus howlandi H. & B. Fragment of upper and lower dental DETECT ETAL AN ee ARO AeA A A ames Ue. | ae Piyeradushowlandi H&B? dental plates. 2.220)... 020. eR Palacmoylus sp.- Fragment dental ‘plate.’)/...00200...0. 0000 ).200! Aspidichthys notabilis Whiteaves. Fragment of plate............ From Onondaga limestone, Buffalo, N. Y.: Demodes bennetti H. & B. Fragments of dental plate. ee. Sree From Rhinestreet shale, eighteen-mile creek, Erie county: Rosdinichinys antiquus He". Wailhamsooy 20022 2028 0 es Van Epps, Percy M., Hoffmans, Schenectady co.: Disc-shaped concretions from Canajoharie shale 1% miles south of SUNEVT STIS MS G1 GUES ASEH I a ClO at Pen Ay ea nN ae aR Reet ar Mathes, K. B., Batavia Elaeocrinus lucina (Hall), Stafford limestone, Stafford, N. Y... Armstrong, E. J., Erie, Pa. Fossil sponges from the Chemung sandstone near Erie, Pa...... PAN OG ThOSSI, ChIMOLGS © 5 soy cceuc's sua stcvage Gpaisis os tee ees he es eons ae Gyrocers stebos Beecher. (cast) Upper Chemung. Conneaut-, Wilke, IB pepe stile, Abe apteee spied ct eee mre AN dell Hd bia ana i a a eat Large slab with specimens of Ceratodictya oryx Clarke. Lower Chenraiag, "omilessouth (of Hirie, Pave. ero ee Beach markings and worm burrows? Lower Chemung, near Erie, JER ‘io ccc ce ORCI AMA IEA ORR Ah Og eS Ee PERM oS Simmons, Alfred, Saugerties Specimen of Ancyrocrinus, Oriskany limestone, Glenerie........ Robinson, W. J., Poughkeepsie Normanskill shale, St Andrews Novitiate. Two miles north of POgankeepsic:. . AIe TOSI. RAE SETS RROD Bod. Deke: ates Bowman, Charles S., Hornell Manticoceras pattersoni, Chemung beds, Hornell, N. Y.......... Burling, L. D., Ottawa Ordovician (top of Deepkill) graptolite shale from Alaska-Yukon pwr ary Aue SUS ey fa, 1 eae oe fey, V5 RR) Sth Ii Ck Shar Yay Caryocaris sp. 5 specimens. Graptolites 2 specimens.............. Deepkill shale at Alaska-Yukon boundary Pohl, Erwin, Albany Rysedorph conglomerate fossils from Rysedorph hill, Rensselaer ONION AME te OO AO an Ore emir cole o ODO cbse acl & CCe Oriol MIRIG fy fOr: Store Gould, Rev. E. W., Bristol, Vt. Fossils from Trenton shale, Panton, Vt...............2.00--05- Ganajoharnie,sualey lake, shore, Panton, Vitis 5 se dacs osadascencees 33 18 eS bo 50 10 34 NEW YORK STATE MUSEUM Cole, Rev. Thomas, Saugerties Oriskany (Glenerie) Glenerie, Ulster county...................-- 509 Onondaga. Split Rock, Onondaga county............ Pee. 2 Tully.. Borodino; Onondaga «county. . 05). 0 4. ce-ch eee ee 4 amltionsSkaneateles laces see yarn ieee eee ahs cee 5 Hamilton. Mount Marion, N. Y............- ica net 13 Schoharie Grit. Ulster co. (?)| Loose Boulder’(?) ... 32.3. sues AI Carboniferous. Mazon. “Greeley oso cyersete seen eee 8 Powers, Sidney W., Tulsa, Okla. Graptolites from) Carter icoumtytOlsla. ste. cece eee 48 slabs Fossils from Ordovician limestone, Carter, Okla.............. 40 slabs Jones, Leslie W., Amsterdam One trilobite and three cephalopods, from Amsterdam limestone, near wAmisterdam, JN.) Vid as eas sche tues 4 acl wheres « nie sak 4 Fossils from Amsterdam limestone, Amsterdam, N. Y............ 9 Reinhard, E., Buffalo Fossils from Ludlowville shale, Athol Springs, N. Y............ 6 Crincid irom Niaearan., Niagara) Hallls;iNi jYi..0 oc sero I Ginn Bros., Mendon Slab of white Potsdam sandstone with trails of Climachtichnites, probably a new species. From the glacial drift on the farm of Ginn Bros., at Mendon Ponds, Monroe county Chadwick, G. H., Rochester Mesopalaeaster sp. Four specimens on one slab. Chemung beds, near Rosses, Livingston co. collected by W. C. Bower......... 5 Hallaster sp. part of arm. Locality and collector same as pre- ceding. Hartley, Robert M., Amsterdam Cryptolithus tesselatus Green. Five slabs with specimens...... 5 Amsterdam limestone in drift. Clark, Burton W., Syracuse Trenton and Utica fossils from Utica quadrangle............... 500 Exchange Reinhard, E., Buffalo Fishes from Onondaga limestone vicinity of Buffalo, N. Y...... 60 Rhinestreet shale. Eighteen-mile creek, Erie co., N. Y......... PA Ra Hibbard, Ray R., Buffalo . Slides*tor Ordovician’ bryozoalsee een eee vile iepie ae eee eee 35 Bryozoans from Ordovician of Ohio basin.......002.Wa. eee 13 Mounted conodonts from Conodont limestone of Genesee shale, Bighteen-mile\ «creek)) Erie comin sy IY 22s nei eee 7 Ward’s Natural Science Establishment, Rochester British tera ptoliies 2.1542) Nae saints « cates «ee cates ee ee 19 REPORT OF THE DIRECTOR IQI9 ,. & Purchase _Ward’s Natural Science Establishment, Rochester . Homalonotus delphinocephalus Green, Rochester shale, Lockport, a etait aya ff. Sorat: « durattt tt.) Aas neat shes aloe. olieaea. Griffithides scitula Meek and Worthen, Pottsvillian, Brazil forma- Rintemacrivaville, Ain ciatiaaweewminid . . oo ssc eels cae coche 020) cae Proetus missouriensis Shumard, Knobstone group. Clark co., Retelteariclne eee Nisa ose ens ek, Spade. bao Pte fae ee Bumastus ioxus (Hall) Rochester shale, Lockport, N. Y........ Lyriocrinus dactylus (Hall) Rochester shale, Lockport, N. Y.. Life size model of the fossil horse (Eohippus).................. ‘Gillard, John, Stafford Fossils from Stafford limestone, Marcellus shale, Onondaga lime- Sonim ceL crm tone SHale fe Bee se ac ee cos ce eles ete Reinhard, E., Buffalo Hennes. poboudlowville, Shale, oioscsc--+csssccescchecscccees Trilobites, Onondaga limestone, Williamsville, N. Y.............. Corals, Onondaga limestone, Williamsville, N. Y................ Bertie Waterlime fossils, Williamsville, N. Y................0.. Telson of Crustacean, Rochester shale, Lockport, N. Y........... Macrostylocrinus ornatus, Rochester shale, Niagara Falls........ Gamoennus, sp4,) Rochester! shale,- Niagara,Falls. .... 0). 5 4-6 o20 208 Pentremites, Hamilton shale, Athol Springs, N. Y.............. Megistocrinus depressus, Hamilton shale, Alden, N. Y........... Pentremites maia (?) Hall Eighteen-mile creek, Erie co.......... Pentremites maia Hall Eighteen-mile creek, Erie co............ Pentremites whitii Hall from Hamilton shale, Athol, Erie co.... Gidley, J. W., Washington, D. C. Six models of the fossil horse (1/5 nat. size) illustrating its evo- } IEG ee RN an ele ACL AE ARE hat A RENO cia SR Oa SP | 7 ay Collection Ruedemann, R. & Hartnagel, C. A. Vernon shale from Barge canal excavation at Pittsford, N. Y. Material from under West shore Railroad bridge............. Hartnagel, C. A. ; Oolitic iron ore fossils from Clinton, N. Y. All specimens show . either the oolitic grains or were obtained from larger blocks which had ore attached. These specimens are from the top of LTE Pal OCP TE NNN AY SINS eset ay eae STN Rap en UPA NS ra Ray stave Ate Sy olfel sy enel ehenc yes etc: Fossils associated with blocky shale at base of oolitic iron-ore. Many specimens show the ore, usually separated from shale by a thin layer of pyrite. The specimens are all from a layer about six inches thick directly below the ore. Borst and Franklin Minresmy @linttoms (Ne Mio): o/esse ee oe ine sein eleiese clsubalandld © aan a Ya 3 j | i 5) Lo N on [o) me ww HN He ee ee ety wb 550 36 NEW YORK STATE MUSEUM Hartnagel, C. A., Wardell, H. C. & Pohl, E. R. Clinton shale one-third of a mile due south of Verona Station. In brook ‘below | dam !4232 2) see eee eee ene Clinton shale 1 mile southwest of Verona Station. In small brook back of house of J. B. Weed, about 15 feet below the fossilione Kupper)! sci: eA ae: yD ehs BE Rae Baars Hartnagel, C. A. Clinton green shale. Red Creek, Wayne co. Creek bank at high- way just north of railroad sta. These shales are above the heavy. \eraptolite jlayersiiy.f. ok. socie This form, Airograptus (Dictyonema) fur- ciferum, occurs in beds 2 and 3 (zone of Didymograptus nitidus and patulus) and the lower part of the zone of Didymo- graptus bifidus, in the Deep Kill section. It is therefore found in about the middle of the Deep Kill section. In Bulletin 189, the species has been placed near the top of the Nittany or the base of the Axeman, while Bassler, in the Biblio- graphic Index, since published, refers the graptolite to the Stone- henge or the basal division of the Bellefonte Beekmantown section. Doctor Ulrich, in a letter dated April 22d, informs me that the latter is the true position of the species, and that this fact agrees with the view, at which he arrived years ago, namely, that the Schaghticoke and Deep Kill graptolite shales hold a position below the middle of the Beekmantown. This view is principally based on evidence obtained in Arkansas. ‘ There,” Doctor Ulrich writes, “the Phyllograptus occurs in the Jefferson city dolomite. Above its zone, with an unconformity intervening, comes a zone with the *R. Ruedemann. Paleontologic Contributions from the New York State Museum. N. Y. State Mus. Bul. 180, p. 20, 1916. A REPORT OF THE DIRECTOR IQIQ 129 ‘nearest approach to the Fort Cassin fauna that I have seen outside of the Champlain valley.” The last of the Deep Kill zones that with Diplograptus dentatus has probably to be excepted from this correlation with the ae and middle Beekmantown (see below, p. 130). The shale with Nemagraptus gracilis has recently been found intercalated, as Athens shale, with fossiliferous limestones in Vir- ginia, by Prof. S. L. Powell, and Drs E. O. Ulrich and George W. _ Stose.?° Raymond, after a critical survey of the evidence furnished in Virginia, considers the section as placing the Normanskill definitely as post-middle Chazy and pre-Trenton and probably upper Chazy age. The writer?’ has in former publications correlated the last zone of the Deep Kill shale that of Diplograptus dentatus, with the Chazy limestone on the ground that it is separated from the preceding zones by a most profound faunal change, namely, that from the Axonolipa to the abruptly appearing Axonophora indicating an - important break between this and the preceding zone. Similarly in Great Britain the zone of Diplograptus dentatus is placed above the Arenig and in Sweden the middle Dicellograptus shales begin with a like outburst of Axonophora, as Diplograptus, Climacograptus, Glossograptus and Cryptograptus. This correlation of the last zone of the Deep Kill shale with the Chazy seems also to be well supported by the stratigraphic nearness of this Deep Kill zone to the Normanskill shale at several localities in our shale belt, as notably on Mount Moreno near Hudson. The descent of the Normanskill shale into line with the upper Chazy, as advocated by Ulrich and Raymond, would then close the gap between the Deep Kill and Normanskill zones. It is expected that the true position of the Rysedorph Hill con- glomerate in regard to the upper Normanskill shale zone of Corynoides calicularis and succeeding graptolite shales, once clearly recognized will furnish sufficient data establishing the age of these shales and of those intervening between the Normanskill and Cana- joharie shales. The intercalation of graptolite shale, carrying Corynoides Peaswculams, Diplosraptis am plextcaulis and Mesograptus mohawkensis in the top of the basal Trenton grap p *See S. L. Powell. Discovery of the Normanskill Graptolite Fauna in the Athens Shale of Southwestern Virginia. Jour. Geol., 1915, v. 23. Percy E. Raymond, op. cit., 1916, p. 234 ff. "See R. Ruedemann, Op. cit., 1902, p. 573 and op. cit., 1904, chart facing D. 490 and p. 408. ; 130 NEW YORK STATE MUSEUM or Glens Falls limestone in the Sprakers and Canajoharie sections?® affords evidence of a direct nature as to the Trenton age of the Canajoharie shale. The Utica shale, like the Canajoharie and Snake Hill shales car- ries mixed graptolite and nongraptolite faunas. Summarizing these correlations of the graptolite facies with the littoral facies we get the following table of approximate correlations : Correlation Table Graptolite facies Littoral facies Utica shale Utica shale Canajoharie shale Trenton limestone Magog, Van Schaick Island, etc.shale Glens Falls and Amsterdam limestone Upper Normanskill shale Lowville and Leray limestone Lower Normanskill shale Upper Chazy limestone Upper Deep Kill (zone of Diplo- Lower and middle Chazy limestone graptus dentatus) Beekmantown limestone and dolo- Lower and middle Deep Kill shale mite Schaghticoke shale Basal Beekmantown dolomite DIAGRAM OF GRAPTOLITE ZONES OF ORDOVICIAN OF NEW YORK Upper Mohawk valley Lower Mohawk and Hudson valleys Atwater Creek shale 20 Z. of Glossogr. quadr. typus Deer River shale 19 Z. of Climac. typic. posteru 18 Z. of Climac. pygmaeus 17_Z. of Dicranogr. nicholsonil Wejenienate 16 Z. of Climacogr. typicalis 15 Z. of Clim. spiniferus | --—~ orviim. spiniferus 14 Z. of Lasiogr. eucharis pa ae eet : Canajoharie shale 13 Z. of Glossogr. quadrimucr. cornutus d Trenton 12 Z. of Diplogr. amplexicaulis Ir Z. of Mesogr. mohawkensis Magog shale 10 Z. of Cryptogr. tricornis insectiformis \ Normanskill shale Black River 9 Z. of Corynoides gracilis Sues 8 Z. of Nemagr. gracilis Chazy 7 Z. of Diplogr. dentatus etc. c Subz. of Trigonogr. ensiformis b Subz. of Phyllogr. angustifolius a Subz. of Climacogr. pungens Canadian 6 Z. greene lies b Subz. of Didymogr. similis (Beekmantown) a Subz. of Goniogr. geometricns Deep Killshale 5 Z. of Didymograptus b Subz. of Didymogr. extensus a Subz. of Didymogr. nitidus 4 Z. of Phyllograptus typus etc. 3 Z. of Clonogr. flexilis, Tetrag:. _ 2 Z. of Staurogr. dichotomus shale Schaghticoke I Z. of Dictyonema flabelliforme © | a SSSeseseFeseseEFese Ozarkian Cambrian *See Ruedemann, op. cit., 1912, p. 22. New York State Museum Joun M. CLARKE, DIRECTOR PUBLICATIONS Packages will be sent prepaid except when distance or weight renders the same impracticable. On 10 or more copies of any one bulletin 20% discount will be given. Editions printed are only large enough to meet special claims and probable sales. When the sale copies are exhausted the price for the few reserve copies is advanced to that charged by secondhand booksellers, in order to limit their distribution to cases of special need. Such prices are inclosed in[ ]. All publications are in paper covers, unless binding is specified. Checks or money orders should be addressed and payable to The University of the State of New York. Museum annual reports 1847—date. All in print to 1894, 50c a volume, 75c in cloth; 1894—date, sold in sets only; 75c each for octavo volumes; price of quarto volumes on application. 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Report Price Report Price Report Price I2 (1892) $.50 17 $.75 ar $.40 14 mS 18 -75 22 -40 15, 2V 2 19 . 40 23 -45 16 I 20 .50 [See Director’s annual reports} Paleontologist’s annual reports 1899-date. See first note under Geologist’s annual reports. Bound also with museum reports of which they form a part. Reports for 1899 and 1900 may be had for 20c each. Those for 1901-3 were issued as bulletins. In 1904 combined with the Director’s report. Entomologist’s annual reports on the injurious and other insects of the State of New York 1882-date. ; Reports 3-20 bound also with museum reports 40-46, 48-58 of which they form a part. Since 1898 these reports have been issued as bulletins. Reports 3-4, 17 are out of print, other reports with prices are: ; Report Price Report Price eport Price 1 $1 : 13 Out of print 24 (Bul. 134) $.35 2 .30 14 (Bul. 23) $.20 DSi (AS NAD) .35 5 .25 i) (C0 31) .15 26( “ 147) BOS 6 215 16( “ 36) .25 DA (ee a5) .40 7 .20 1g(“ 64) © 220 28( “ 165) .40 8 .25 19( “ 76) .15 QOS 175) .45 9 “25 20( “ 97) -40 30( “ 180) -50 10 .35 21( “ 104) nS 31( “ 186) .35 11 25) 22( “ 110) .25 32( “ 198) .40 12 ADS) 23.( “ 124) 75 : 33 ( “ 202) .35 Pe enor 2, 8-12 may also be obtained bound in cloth at 25c each in addition to the price given above. : 132 NEW YORK STATE MUSEUM Botanist’s annual reports 1867-date. Bound also with museum reports 21-date of which they form a part; the first Botanist’s report appeared in the 21st museum report and is numbered 21. Reports 21-24, 29, 31-41 were not published separately. Separate reports for 1871-74, 1876, 1888-98 are out of print. Report for 1899 may be had for 20c; 1900 for 50c. Since 1901 these reports have been issued as bulletins. Descriptions and illustrations of edible, poisonous and unwholesome fungi of New York have also been published in volumes 1 and 3 of the 48th (1894) museum report and in volume 1-of the 49th (1895), 51st (1897), 52d (1898), 54th (1900), 55th (1901), in volume 4 of the 56th (1902), in volume 2 of the 57th (1903), in volume 4 of the 58th (1904), in volume 2 of the 59th (1905), in volume I of the 60th (1906), in volume 2 of the 61st (1907), 62d (1908), 63d (1909), 64th (1910), 65th (1911), v. 2 of the 66th (1912) reports. The descriptions and illustrations of edible and unwholesome species contained in the 40th, 51st and 52d reports have been revised and rearranged, and, combined with others more recently prepared, constitute Museum Memoir 4. Museum bulletins 1887—date. ogy, mineralogy; (4) entomology. 8vo. (1) geology, economic geology, paleontol- (2) general zoology, archeology, miscellaneous; (3) botany, Bulletins are grouped in the list on the following pages according to divisions. The divisions to which bulletins belong are as follows: t Zoology 59 Entomology 117 Archeology 2 Botany 60 Zoology 118 Geology 3 Economic Geology 61 Economic Geology 119 Economic Geology 4 Mineralogy 62 Miscellaneous 120 % © 5 Entomology 63 Geology 121 Director’s report for 1907 6 # 64 Entomology 122 Botany 7 Economic Geology 65 Paleontology 123 Economic Geology 8 Botany 66 Miscellaneous 124 Entomology 9 Zoology 67 Botany 125 Archeology to Economic Geology 68 Entomology 126 Geology Ir e z 69 Paleontology I27 ¢ 12 A s 70 Mineralogy 128 « 13 Entomology 71% Zoology 129 Entomology 14 Geology 72 Entomology 130 Zoology 15 Economic Geology 73 Archeology I3I Botany 16 Archeology 74 Entomology 132 Economic Geology 37 Economic Geology 75 Botany 133 Director’s report for 1908 48 Archeology 76 Entomology 134 Entomology ag Geology 77 Geology 135 Geology 20 Entomology 78 Archeology 136 Entomology 21 Geology 79 Entomology 137 Geology 22 Archeology 80 Paleontology 138 e 23 Entomology 8i Geology 139 Botany 24 a 82 Ms 140 Director’s report for 1909 25 Botany 83 3 141 Entomology 26 Entomology 84 £ f 142 Economic Geology 27 : 85 Economic Geology 143 i is 28 Botany 86 Entomology 144 Archeology 29 Zoology 87 Archeology 145 Geology 30 Economic Geology 88 Zoology 146 . 31 Entomology 80 Archeology 147 Entomology 32 Archeology 90 Paleontology 148 Geology 33 Zoology 9t Zoology 149 Director’s report for 1910 34 Geology 02 Geology and Paleontology 150 Botany 35 Economic Geology 93 Economic Geology 151 Economic Geology 36 Entomology 94 Botany 152 Geology 37 % 95 Geology 153 : 38 Zoology 96 e 154 & 39 Paleontology 97 Entomology 155 Entomology 40 Zoology 98 Mineralogy 156 " 41 Archeology 99 Geology 157 Botany 42 Geology 100 Economic Geology 158 Director's report for 1911 &3 Zoology 10rt Geology 159 Geology 44 Economic Geology 102 Economic Geology 160 e 45 Geology and Paleontology 103 Entomology 161 Economic Geology 46 Entomology 104 ¢ 162 Geology 47 . to5 Botany 163 Archeology 48 Geology 106 Geology 164 Director’s report for 1912 49 Paleontology 107 Geology and Paleontology 165 Entomology 4 «Archeology 108 Archeology 166 Economic Geology 5 :Zoology 109 Entomology 167 Botany 52 Paleontology Ito ¢ 168 Geology 53 Entomology tir Geology 169 & 54 Botany 112 Economic Geology 170 ia 55 Archeology 113 Archeology I7I 5 86 Geology 114 Geology By!) ie 57 Entomology Its C 173 Director’s report for 1913 s8 Mineralogy 1i6 Botany 174 Economic Geology REPORT OF THE DIRECTOR IQI9Q 133 175 Entomology 188 Botany 201 Economic Geology 176 Botany 189 Paleontology 202 Entomology 177 Director’s report for 1914 I90 Economic Geology 203-204 Economic Geology 178 Economic Geology 191 Geology : 205-206 Botany 179 Botany 192 We 207-208 Director's report for - 180 Entomology 193 i IQI7 181 Economic Geology 194 Entomology 209-210 Geology 182 Geology 195 Geology 211-212 ts 183 Geology 196 Director’s report for 1916 213-214 ss 184 Archeology 197 Botany 215-216 ee 185 Geology 198 Entomology . 217-218 e 186 Entomology I99 Economic Geology 219-220 Director's report for 187 Director's report for 1915 200 Entomology ; Io18 Bulletins are also found with the annual reports of the museum as follows: Bulletin Report Bulletin Report Bulletin Report Bulletin Report I2-I5 48,v.1 78 Bivins II7 60,v.3 165-67 66,v.2 16,17 50,v.1 79 57,Vv.1I,pt2 118 60,v.1 168-70 66,v.1 18,19 51,v.1I 80 57,V.1I,ptI I19-21 6I,v.I 171-76 67 20-25 52,v.1 81, 82 58,v.3 I22 6I1,v.2 177-80 68 26-31 53,Vv.1 83, 84 58,v. 1 123 6I,v.I 181 69, v. 2 32-34 54,Vv.1 85 58,v. 2 I24 6I,v.2 182,183 69,v.1 35,36 54,v.2 86 58,Vv.5 I25 62,v.3 184 69, Vv. 2 37-44 54,V.3 87-89 58,v.4 126-28 62,v.I 185 69, v. I 45-48 54,Vv.4 90 58, v.3 129 62,v.2 186 60, V. 2 49-54 55 OI 58, v. 4 130 62,v.3 187 69, v. I 55 56, v. 4 92 58, v.3 I3I,132 62,v.2 188 69, v. 2 56 56, v.1 93 58, v. 2 133 62,v.I 189 690, v. I 57 56,v.3 94 58, Vv. 4 134 62,v.2 190 69, v. 2 58 56, v. I 95, 96 58,v.1 135 63, v. I 59,60 56,v.3 97 58,v.5 136 63,Vv.2 Memoir I Rey atau 98, 99 59, Vv. 2 137,138 63,v.I 2° 49,v.3,and50,v.2 62 56,v.4 roo 59, v. I 139 63,V.2 3,4 53,V.2 63 56, v. 2 IOL 50, v. 2 140 63,v.I 5,6 57,V-3 64 56, Vv. 3 102 59, Vv. I 141-43 63,Vv.2 7 57,V.4 65 56, v. 2 103-5 50,Vv.2. I44 64,v.2 8, ptI 59, Vv.3 66,67 56,Vv.4 106 50, Vv. 1 145,146 64,v.1 8, pt2 59,v.4 68 56, v.3 107 60, v. 2 147,148 64,v.2 9,ptI 60, v. 4 - 690 56, v. 2 108 60, v. 3 -I49 64,v.I 9,pt2 62,Vv.4 70,71 57,Vv.1,ptI I09, I10 60, Vv. I 150-54 64,Vv.2 £0 60, v. 5 72 57, v.1I, pt 2 IIt 60, v. 2 155-57 65,Vv.2 II 61, v.3 73 Bina II2 60, v. I 158-60 65,Vv.I1 12,ptI 63,v.3 74 57, v. I, pt 2 II3 60, v. 3 I6r 65,Vv.2 12,pt2 66,v.3 75 57, Vv. 2 II4 60, v. I 162 65,Vv.I 13 63,V.4 76 S7ANe Ly pte II5 60, v. 2 163 66,v.2 14,v.1I 65,v.3 77 57, Vv. 1, ptt I16 60, v. I 164 66,v.I 1I4,v.2 65,v.4 The figures at the beginning of each entry in the following list indicate its number as a museum bulletin. Geology and Paleontology. 14 Kemp, J. F. Geology of Moriah and West- port Townships, Essex Co., N. Y., with notes on the iron mines. 38p. il. 7pl.2 maps. Sept. 1895. Free. 19 Merrill, F. J. H. Guide to the Study of the Geological Collections of the New York State Museum. 164p. 119 pl. map. Nov. 1898. Out of print. 21 Kemp, J. F. Geology of the Lake Placid Region. 24p. Ipl. map. Sept. 1898. Free. 34 Cumings, E. R. Lower Silurian System of Eastern Montgomery County; Prosser, C. S. Notes on the Stratigraphy of Mohawk Valley and Saratoga County, N. Y. 74p.14pl.map. May 1goo. 15¢. 39 Clarke, J. M.; Simpson, G. B. & Loomis, F. B. Paleontologic Papers 1. 72p. il. 16pl. Oct. 1900. I5c. Contents: Clarke, J. M. A Remarkable Occurrence of Orthoceras in the Oneonta Beds of the Chenango Valley, N. Y. Paropsonema cryptophya; a Peculiar Echinoderm from the Intumescens-zone (Portage Beds) of Western New York. i — Dictyonine Hexactinellid Sponges from the Upper Devonic of New York. — The Water Biscuit of Squaw Island, Canandaigua Lake, N.Y. Simpson, G. B. Preliminary Descriptions of New Genera of Paleozoic Rugose Corals. Loomis, F. B. Siluric Fungi from Western New York. 42 Ruedemann, Rudolf. Hudson River Beds near Albany and. Their Taxo- nomic Equivalents. 116p.2pl.map. Apr. 1901. 25c. 45 Grabau, A. W. Geology and Paleontology of Niagara Falls and Vicinity. 286p. il. 18pl. map. Apr. 1901. 65¢; cloth, goc. 134 NEW YORK STATE MUSEUM 48 Woodworth, J. B. Pleistocene Geology of Nassau County and Borough of Queens. 58p. il. 8pl. map. Dec. 1901. Out of print. 49 Ruedemann, Rudolf; Clarke, J. M. & Wood, Elvira. Paleontologic Papers 2. 240p. 13pl. Dec. 1901. Out of print. Contents: Ruedemann, Rudolf, Trenton Conglomerate of Rysedorph Hill. Clarke, J. M. Limestones of Central and Western New York Interbedded with Bituminous Shales of the Marcellus Stage. Wood, Elvira. Marcellus Limestones of Lancaster, Erie Co., N. Y. Clarke, J. M. New Agelacrinites. Value of Amnigenia as an Indicator of Fresh-water Deposits during the Devonic of New York, Ireland and the Rhineland. 52 Clarke, J. M. Report of the State Paleontologist 1901. 28op. il. ropl. map. Itab. July 1902. 4oc. 56 Merrill, F. J. H. Description of the State Geologic Map of 1901, 42p. 2 maps, tab. Nov. 1902. Free. 63 Clarke, J. M. & Luther, D. D. Stratigraphy of Canandaigua and Naples ' Quadrangles. 78p. map. June 1904. 25c. 65 Clarke, J. M. Catalogue of Type Specimens of Paleozoic Fossils in the New York State Museum. 848p. May 1903. $1.20, cloth. 69 Report of the State Paleontologist 1902. 464p. 52pl. 7 maps. Nov. 1903. $1, cloth. 77 Cushing, H. P. Geology of the Vicinity of Little Falls, Herkimer Co. 98p. il. 15 pl.2maps. Jan. 1905. 30c. . 80 Clarke, J. M. Revert of the State Paleontologist 1903. 396p. 2gpl. 2 maps. Feb. 1905. 85¢c, cloth. 81 Clarke, J. M. & Luther, D. D. Watkins and Elmira Quadrangles. 32p. map. Mar. 1905. 25c. 82 Geologic Map of the Tully Quadrangle. 4op. map. Apr. 1905. 20c. 83 Woodworth, J. B. Pleistocene Geology of the Mooers Quadrangle. 62p. 25pl. map. June 1905. 25¢. Ancient Water Levels of the Champlain and Hudson Valleys. 206p. il. rrpl. 18 maps. July 1905. 45c. 90 Ruedemann, Rudolf. Cephalopoda of Beekmantown and Chazy Forma- tions of Champlain Basin. 224p. il. 38pl. May 1906. 75¢c, cloth. 92 Grabau, A. W. Guide to the Geology and Paleontology of the Schoharie Region. 314p. il. 26pl. map. Apr. 1906. 75¢c, cloth. 95 Cushing, H. P. Geology of the Northern Adirondack Region. 188p. 15pl. 3maps. Sept. 1905. 30c. 96 Ogilvie, I. H. Geology of the Paradox Lake Quadrangle. 54p. il. 17pl. map. Dec. 1905. 30¢. 99 Luther, D. D. Geology of the Buffalo Quadrangle. 32p. map. May 1906. 20c. IoI Geology of the Penn Yan-Hammondsport Quadrangles. 28p. map. July 1906. Out of print. 106 Fairchild, H. L. Glacial Waters in the Erie Basin. 88p. 14pl. 9 maps. Feb. 1907. Out of print. 107 Woodworth, J. B.; Hartnagel, C. A.; Whitlock, H. P.; Hudson, G. H.; Clarke, J. M.; White, David & Berkey, C. P. Geological Papers. 388p. 54pl. map. May 1907. 900, cloth. Contents: Woodworth, J. B. Postglacial Faults of Eastern New York. Hartnagel, C. A. Stratigraphic Relations of the Oneida Conglomerate. Upper Siluric and Lower Devonic Formations of the Skunnemunk Mountain Region. Whitlock, H. P. cay from Lyon Mountain, Clinton Co. Hudson, G. H. On Some Pelmatozoa from the Chazy Limestone of New York. Clarke, J. M. Some New Devonic Fossils. An Interesting Style of Sand-filled Vein. Eurypterus Shales of the Shawangunk Mountains in Eastern New York. White, David. A Remarkable Fossil Tree Trunk from the Middle Devonic of New York. Berkey, C. P. Structural and Stratigraphic Features of the Basal Gneisses of the Highlands. 111 Fairchild, H. L. Drumlins of New York. 6op. 28pl. 19 maps. July 1907. Out of print. 114 Hartnagel, C. A. Geologic Map of the Rochester and Ontario Beach Quad- tangles, 36p. map. Aug. 1907. 20¢c. ” i : ; i : ‘ ; i REPORT OF THE DIRECTOR IQIQ 135 115 Cushing, H. P. Geology of the Long Lake Quadrangle. 88p. 2opl. map. Sept. 1907. 25c. 118 Clarke, J. M. & Luther, D. D. Geologic Maps and Descriptions of the Portage and Nunda Quadrangles including a map of Letchworth Park. s5op. 16pl. 4 maps. Jan. 1908. 35c. 126 Miller, W. J. Geology of the Remsen Quadrangle. 54p. il. r1pl. map. Jan. 1909. 25¢c. 127 Fairchild, H. L. Glacial Waters in Central New York. 64p. 27pl. 15 maps. Mar. 1909. 40Cc. 128 Luther, D. D. Geology of the Geneva-Ovid Quadrangles. 44p. map. Apr. 1909. 20c. 135 Miller, W. J. Geology of the Port Leyden Quadrangle, Lewis County, Rays o2p. 31) rrpl. map. Jan. r9ro0. 25. 137 Luther, D. D. Geology of the Auburn-Genoa Quadrangles. 36p. map. Mar. 1910. 20c. 138 Kemp, J. F. & Ruedemann, Rudolf. Geology of the Elizabethtown and Port Henry Quadrangles. 176p. il. 20pl.3 maps. Apr. 1910. Out of print. 145 Cushing, H. P.; Fairchild, H. L.; Ruedemann, Rudolf & Smyth, C. H. Geology of the Thousand Islands Region. 194p. il. 62pl. 6 maps. Dec. 1910. $1, cloth. 146 Berkey, C. P. Geologic Features and Problems of the New York City (Catskill) Aqueduct. 286p. il. 38pl. maps. Feb. 1911. 75c; $1, cloth. 148 Gordon, C. E. Geology of the Poughkeepsie Quadrangle. 122p. il. 26pl. map. Apr. I9QII. 30c. 152 Luther, D. D. Geology of the Honeoye Wayland Quadrangles. 3op. map. Oct. I9II. 20c. 153 Miller, William J. Geology of the Broadalbin Quadrangle, Fulton-Saratoga Counties, New York. 66p. il. 8pl. map. Dec. 1911. 25c. 154 Stoller, James H. Glacial Geology of the Schenectady Quadrangle. 44p. gpl. map. Dec. 1911. 20c. 159 Kemp, James F. The Mineral Springs of Saratoga. 8op. il. 3 pl. Apr. 1912. I5¢. 160 Fairchild, H. L. Glacial Waters in the Black and Mohawk Valleys. 48p. il. 8pl. 14 maps. May 1912. 50c. 162 Ruedemann, Rudolf. The Lower Siluric Shales of the Mohawk Valley. 152p. il. r5pl. Aug. 1912. 35c. 168 Miller, William J. Geological History of New York State. 130p. 43pl. 10 maps. Dec. 1913. 40c. ~ 169 Cushing, H. P. & Ruedemann, Rudolf. Geology of Saratoga Springs and _ Vicinity. 178p.il. 2opl.map. Feb. 1914. 40c. 170 Miller, William J. Geology of the North Creek Quadrangle. gop. il. r4pl. Feb. 1914. 25¢c. 171 Hopkins, T. C. The Geology of the Syracuse Quadrangle. 8op. il. 2opl. map. July 1914. 25c. 172 Luther, D. D. Geology of the Attica and Depew Quadrangles. 32p. map. Aug. I914. I5¢c. ; 182 Miller, William J. The Geology of the Lake Pleasant Quadrangle. 56p. il. topl. map. Feb. 1916. 25c. 183 Stoller, James H. Glacial Geology of the Saratoga Quadrangle. 5op. il. 12pl.map. Mar. 1, 1916. 25c. 185 Martin, James C. The Precambrian Rocks of the Canton Quadrangle. 112p. il. 2opl. map. May 1, 1916. 30c. 189 Ruedemann, Rudolf. Paleontologic Contributions from the New York State Museum. 225p.il.36 pl. Sept. 1916. 5o0c. ror Cushing, H. P. Geology of the Vicinity of Ogdensburg. 64p. il. 6pl. map. “Nov. 1916. 25c. 192 Miller, William J. Geology of the Blue Mountain Quadrangle. 68p. il. 1ipl.map. Dec. 1916. 25c. 193 The Adirondack Mountains. 97p. il. 3opl.2 maps. Jan. 1917. 35c. 195 Fairchild, H. L. Postglacial Features of the Upper Hudson Valley. 22p.. map. Mar. 1, 1917. 25c. 136 NEW YORS® STATE MUSEUM 209-210 Fairchild, H. L. Pleistocene Marine Submergence of the Hudson, Champlain and St Lawrence Valleys. 75p. il. 25pl. maps. May-June 1918. 50c. 211-212 Miller, W. J. Geology of the Lake Placid Quadrangle. 1o4p. il. 23pl. map. July—Aug. 1918. 35¢. 213-214 Geology of the Schroon Lake Quadrangle. t1o2p. il. 14pl. map. Sept.— Oct. 1918. 35¢c. one Tai6 Stoller, J. H. Glacial Geology of the Cohoes Quadrangle. 4op. il. 2pl. map. Nov.—Dec. I9IQ. 25¢. Bie Chadwick, George H. Paleozoic Rocks of the Canton Quadrangle. 6op. il.t2pl. map. Jan.—Feb. 1919. 35c. 221-222 Clarke, John M. Organic Dependence and Disease. Their origin and significance. 225-226 Berkey, C. P. & Rice, Marion. Geology of the West Point Quad- rangle. p- pl.map. Sept.—Oct. 1919. Crosby, W. O. Geology of Long Island. Jn preparation. Luther, D. D. Geology of the Phelps Quadrangle. In preparation. —— Geology of the Eden-Silver Creek Quadrangles. Prepared. Geology of the Brockport-Hamlin and Albion-Oak Orchard Quadrangles. Prepared. Geology of the Medina-Ridgeway and Lockport-Olcott Quadrangles. Prepared. Geology of the Caledonia-Batavia Quadrangles. Prepared. Ruedemann, R. The Utica and Lorraine Formations of New York. In prepara- tion. Kemp, James F. Geology of the Mount Marcy Quadrangle. In press. . Miller, W. J. Geology of the Lyon Mountain Quadrangle. Prepared. Cushing, H. P. Geology of the Gouverneur Quadrangle. Prepared. tee F. & Alling, H. L. Geology of the Ausable Quadrangle. Pre- pare Smyth, C. H. jr & Buddington, A. F. Geology of the Lake Bonaparte Quad- tangle. Prepared. Miller, W. J. Geology of the Russell quadrangle. Prepared. Cook, J. H. Surface Geology of the Albany-Berne Quadrangles. Prepared. Buddington, A. F. Geology of the Lowville Quadrangle. Prepared. _ Fairchild, H. L. Evolution of the Susquehanna River. Prepared. Economic Geology. 3 Smock, J. C. Building Stone in the State of New York 154 p. Mar. 1888. 30c. ¥ 7 First Report on the Iron Mines and Iron Ore Districts in the State of New York. 78p. map. June 1889. 25c. 10 Building Stone in New York. 210p. map, tab. Sept. 1890. 40c. 1r Merrill, F. J. H. Salt and Gypsum Industries of New York. 94p. 12pl. 2maps, 11 tab. Apr. 1893. 50c. 12 Ries, “olhigh Clay Industries of New York. 174p. il. Ipl. map. Mar. 1895. 15 Merit E ah H. Mineral Resources of New York. 240p. 2 maps. Sept. 1895. _[50c] 17 Road Materials and Road Building in New York. 52p. 14pl. 2 maps. Oct. 1897. 15¢c. 30 Orton, Edward. Petroleum and Natural Gas in New York. T36peail, || 3 maps. Nov.1899. I5¢c. 35 Ries, Heinrich. Clays of New York; Their Properties and Uses. 456p. 140pl. map. June tgoo. $1, cloth. Lime and Cement Industries of New York; Eckel, E. C. Chapters on the Cement Industry. 332p. 1oIpl. 2 maps. Dec. 1901. 85¢c, cloth. 61 Dickinson, H. T. Quarries of Bluestone and Other Sandstones in New York. 114p. 18pl.2 maps. Mar. 1903. 35c. 85 Rafter, G. W. Hydrology of New York State. go2p. il. 44pl. 5 maps. May 1905. $1.50, cloth. 93 Newland, D. H. Mining and Quarry Industry of New York. 78p. July 1905. Out of print. too McCourt, W. E. Fire Tests of Some New York Building Stones. 4op. 26pl. Feb. 1906. 15c. } : } REPORT OF THE DIRECTOR I9QI19 137 102 Newland, D. H. Mining and Quarry Industry of New York 1905. 162p. June 1906. 25¢c. 112 Mining and Quarry Industry of New York 1906. 82p. July 1907. Out of print. IIQ & Kemp, J. F. Geology of the Adirondack Magnetic Iron Orés with a Report on the Mineville-Port Henry Mine Group. 184p. 14pl. 8 maps. Apr. 1908. 35¢c. 120 Newland, D. H. Mining and Quarry Industry of New York 1907. 82ap. July 1908. 15¢c. 123 & Hartnagel, C. A. Iron Ores of the Clinton Formation in New York State. 76p. il. 14pl. 3 maps. Nov. 1908. 25c. 132 Newland,-D. H. Mining and Quarry Industry of New York 1908. 98p. July 1909. I5¢c. 142 Mining and Quarry Industry of New York for 1909. 98p. Aug. Igto. 15c. : 143 Gypsum Deposits of New York. 94. 2opl. 4 maps. Oct. 1910. 35¢. 151 —— Mining and Quarry Industry of New York i910. 82p. JuneIgit. I5c. 161 —— Mining and Quarry Industry of New York 1911. 114p. July 1912. 20¢. 166 Mining and Quarry Industry of New York 1912. I14p. Aug. 1913. 200. I74 Mining and Quarry Industry of New York 1913. 1ItIp. Dec. 1914. 20¢. 178 Mining and Quarry Industry of New York 1914. 88p. Nov. 1915. 15¢. 181 —— The Quarry Materials of New York. 212p. 34pl. Jan. 1916. 400. 190 —— Mining and Quarry Industry of New York 1915. 92p. Oct. 1916. I5¢. . —— Mining and Quarry Industry of New York (see Mus. Bul. 196). 199 Alling, Harold L. The Adirondack Graphite Deposits. 15o0p. il. July 1, 1917. 30c 201 Smyth, C. H., jr. Genesis of the Zinc Ores of the Edwards District, St Lawrence County, N. Y. 32p. 12pl. Sept. 1, 1917. 20¢. 203-204 Colony, R. J. High Grade Silica Materials for Glass, Refractories and Abrasives. 31p. il. Nov.—Dec. 1917. 15¢c. 223-224 Newland, D.H. The Mineral Resources of the State of New York. 3i5p.il. 3 maps. July-August 19179. 5o0c. i ‘ Prepared. Mineralogy. 4 Nason, F. L. Some New York Minerals and Their Localities. 22p. Ipl. Aug. 1888. Free. 58 Whitlock, H. P. Guide to the Mineralozie Collections of the New York State Museum. 150p. il. 39pl. rr models. Sept. 1902. doc. 70 —— New York Mineral Localities. r1op. Oct. 1903. 20c. 98 —— Contributions from the Mineralogie Laboratory. 38p. 7pl. Dec 1905. Out of print. Zoology. 1 Marshall, W. B. Preliminary List of New York Unionidae. 20p Mar. 1892. Free. 9 —— Beaks of Unionidae Inhabiting the Vicinity of Albany, N. Y. 30p. Ipl. Aug. 1899. Free. 29 Miller, G. S. jr. Preliminary List of New York Mammals. 124p. Oct. 1899. 15¢. 33 Farr, M.S. Check List of New York Birds. 224p. Apr. 1900. 25¢c. 38 Miller, G. S. jr. Key to the Land Mammals of Northeastern North America. 1o6p. Oct. 1900. 15c. 40 Simpson, G. B. Anatomy and Physiology of Polygyra aibolabris and Limax maximus and Embryology of Limax maximus. 82p. 28pl. Oct. Igo0I. 25¢. 43 Kellogg, J. L. Clam and Scallop Industries of New York. 36p. 2pl. map. Morapr. LOOK.” ree. 51 Eckel, E. C. & Paulmier, F. C. Catalogue of Reptiles and Batrachians of New York. 64p.il. ipl. Apr. 1902. Out of print. _ Eckel, E. C. Serpents of Northeastern United States. Paulmier, F. C. Lizards, Tortoises and Batrachians of New York. 69 ne T. H. Catalogue of the Fishes of New York. 784p. Feb. 1903. $1 cloth. 138 NEW YORK STATE MUSEUM 71 Kellogg, J. L. Feeding Habits and Growth of Venus mercenaria. 30p 4 pl. Sept. 1903. Free. 83 Letson, Elizabeth J. Check List of the Mollusca of New York. 116p. May 1905. 20c. or Paulmier, F. C. Higher Crustacea of New York City. 78p. il. June 1905. - + 20C. _ 130 Shufeldt, R. W. Osteology of Birds. 382p. il. 26p!. May 1909. 50c. Entomology. 5 Lintner, J. A. White Grub of the May Beetle. 34p. il. Nov. 1888. Free. 6 —— Cut-worms. 38p.il. Nov. 1888. Free. 13 San José Scale and Some Destructive Insects of New York State. 54p. 7pl. Apr. 1895. I5¢. 20 Felt, E. P. Elm Leaf Beetle in New York State. 46p. il. 5pl. June 1898. Free. See 57. 23 20¢. 24 —— Memorial of the Life and Entomologic Work of J. A. Lintner Ph.D. State Entomologist 1874-98; Index to Entomologist’s Reports I-13. 316p. ipl. Oct. 1899. 35c. Supplement to 14th report of the State Entomologist. 26 14th Reoort of the State Entomologist 1898. r5o0p. il. 9pl. Dec. 1898. Collection, Preservation and Distribution of New York Insects. 36p. il. Apr. 1899. Out of print. 27 Shade Tree Pests in New York State. 26p. il. 5pl. May 1899. Out of print. 31 15th Report of the State Entomologist 1899. 128p. June 1900. I5¢. 36 —— 16th Report of the State Entomologist 1900. 118p. 16pl. Mar. I90I. 25¢. CHaletic of Some of the More Important Injurious and Beneficial Insects of New York State. 54p.il. Sept. 1900. Free. 46 Scale Insects of Importance and a List of the Species in New York State. g4p. il. r5pl. June rgor. 25c. 47 Needham, J. G. & Betten, Cornelius. Aquatic Insects in the Adirondacks. 234p. il. 36pl. Sept. r901. 45c. 53 Felt, E. P. 17th Report of the State Entomologist 1901. 232p. il. 6pl. Aug. 1902. Out of print. Elm Leaf Beetle in New York State. 46p. il. 8 pl. Aug. 1902. Out of print. This Fy a revision of Bulletin 20 containing the more essential facts observed since that was prepared. 57 59 Grapevine Root Worm. 4o0p.6pl. Dec. 1902. 15¢. See 72. 64 18th Report of the State Entomologist 1902. 1110p. 6 pl. May 1903. 20¢. 68 Needham, J. G. & others. Aquatic Insects in New York. 322p. 52pl. Aug. 1903. 80c, cloth. 72 Felt, E. P. Grapevine Root Worm. 58p. 13pl. Nov. 1903. 20¢c. This is a revision of Bulletin 59 containing the more essential facts observed since that was prepared, 74 & Joutel, L. H. Monograph of the Genus Saperda. 88p. r4pl. June 1904. 25¢. set ee E. °P. 19th Report of the State Entomologist 1903. 1I50p. 4pl. 1904. 164p. il. 57pl. tab. Oct. 1904. 86" Meee J. G. & others. May Flies and Midges of New York. 352p. il. 37pl. June 1905. 80c, cloth. 97 Felt, E. P. 20th Report of the State Entomologist 1904. 246p. il. ropl. Nev. 1905. 40c. REPORT OF THE DIRECTOR IQIQ 139 103 —— Gipsy and Brown Tail Moths. 44p. 1opl. July 1906. Out of print. 104 —— 21st Report of the State Entomologist 1905. 1144p. r1opl. Aug. 1906. a Tussock Moth and Elm Leaf Beetle. 34p. 8pl. Mar. 1907. Out of lal 22d Report of the State Entomologist 1906. 1152p. 3pl. June 1907. pi 23d Report of the State Entomologist 1907. 542p. il. 44pl. Oct. 1908. 75c. 129 Control of Household Insects. 48p.il. May 1909. Out of print. 134 24th Report of the State Entomologist 1908. 208p. il. 17pl. Sept. 1909. 35¢. 136 Control of Flies and Other Household Insects. 56p. il. Feb. 1910. 15¢c. This i: a revision of Bulletin 129 containing the more essential facts observed since that was prepared. : _ 141 Felt, E. P. 25th Report of the State Entomologist 1909. 178p. il. 22pl. July 1910. 35¢c. 147 —— 26th Report of the State Entomologist 1910. 182p. il. 35pl. Mar. FOUT.1, 35C- 155 27th Report of the State Entomologist 1911. 198p. il. 27pl. Jan. 1912. 40c. viet 156 Elm Leaf Beetle and White-Marked Tussock Moth. 35p. 8pl. Jan. I9I2. 20c. 165 28th Report of the State Entomologist 1912. 266p. 14pl. July 1913. “Sane 29th Report of the State Entomologist 1913. 258p. 16pl. April 1915. a 30th Report of the State Entomologist 1914. 336p. il. 19pl. Jan. ae Sree Report of the State Entomologist 1915. 215p. il. 18pl. June 1, al Boevetiald and Camp Insects. 84p.il. Feb. 1, 1917. 15¢c. 198 —— 32d Report of the State Entomologist 1916. 276p. il. 8pl. June 1, ae ies to American Insect Galls. 310p. il. 16pl. August 1917. Out of ae 33d Report of the State Entomologist 1917. 24o0p. il. 12pl. 35¢. Betten, Cornelius. Report on the Aquatic Insects of New York. In press. Felt, E. P. Report of the State Entomologist for 1918. Prepared. Botany. 2 Peck, C.H. Contributions to the Botany of the State of New York. 72p. 2pl. May 1887. . 20c. 8 Boleti of the United States. 98p. Sept. 1889. Out of print. 25 Report of the State Botanist 1898. 76p. 5pl. Oct. 1899. Out of print. 200. 28 Plants of North Elba. 206p.map. June 1899. 20c. 54 Report of the State Botanist 1901. 58p.7pl. Nov. 1902. 4oc. 67 Report of the State Botanist 1902. 196p. 5pl. May 1903. 5o0c. 75 —— Report of the State Botanist 1903. 7op. 4pl. 1904. 40c. 04. Report of the State Botanist 1904. 6o0p. 10pl. July 1905. 4oc. 105 Report of the State Botanist 1905. 108p. 12pl..Aug. 1906. 5o0c. 116 Report of the State Botanist 1906. 1120p. 6pl. July 1907. 365¢c. 122 Report of the State Botanist 1907. 178p. 5pl. Aug. 1908. 4oc. 131 —— Report of the State Botanist 1908. 202p. 4pl. July 1909. 4oc. 139 Report of the State Botanist 1909. 116p. 1opl. May 1910. .45¢c. 150 Report of the State Botanist I910. Ioop. 5pl. May 1911. 30. 157 Report of the State Botanist 1911. 140p.9pl. Mar. 1912. 35¢. 167 Report of the State Botanist 1912. 138p.4pl. Sept. 1913. 30c. 176 Report of the State Botanist 1913. 78p.17pl. June 1915. 20c. 179 Report of the State Botanist 1914. 108p.1pl. Dec. 1915. 20c. 188 House, H. D. Report of the State Botanist 1915. 118p. il. gpl. Aug. 1, I916. 30c. 140 ; NEW YORK STATE MUSEUM 197 ---— Report of the State Botanist 1916. 122p. 11pl. May I, 1917. 30c. 205- 2c6 —— Report of the State Botanist 1917. 169p. 23pl. Jan.—Feb. r9r8. 50¢. : Archeology. 16 Beauchamp, W. M. Aboriginal Chipped Stone Implements of New York. 86p. 23pl. Oct. 1897. 25¢c. 18 Polished Stone Articles Used by the New York Aborigines. 104p. 35pl. Nov. 1897. 25c. ‘ 22 Earthenware of the New York Aborigines. 78p. 33pl. Oct. 1898. 25¢c. 32 —— Aboriginal Occupation of New York. 190p. 16pl. 2 maps. Mar. 1900. 30¢. 41 Wampum and Shell Articles Used by New York Indians. 166p. 28pl. Mar. 1901. Out of print. Horn and Bone Implements of the New York Indians. 112p. 43pl. Mar. 1902. Out of print. 50 g4p. 38pl. June 1902. 25¢ 73 Metallic Ornaments of the New York Indians. 122p. 37pl. Dec. 1903. Out of print. 78 —— History of the New York Iroquois. 340p. 17pl. map. Feb. 1905. Out of print. 87 Perch Lake Mounds. 84p. 12pl. Apr. 1905. 20c. 89 Aboriginal Use of Wood in New York. gop. 35pl. June 1g05. Out of print, 108 Aboriginal Place Names of New York. 336p. May 1907. Out of print. 113 Civil, Religious and Mourning Councils and Ceremonies of Adoption. 118p. 7pl. June 1907. 25¢c. 117 Parker, A. C. An Erie Indian Village and Burial Site. t1o2p. 38pl. Dec. 1907. 30. 125 Converse, H. M. & Parker, A. C. Iroquois Myths and Legends. rg6p. il. rrp]. Dec. 1908. S5o0c. 144 Parker, A.C. Iroquois Uses of Maize and Other Food Plants. 120p. il. 31pl. Nov. 1910. Out of print. 163 The Code of Handsome Lake. 144p. 23pl. Nov. 1912. 25¢. 184—— The Constitution of the Five Nations. 158p. 8pl. April1, 1916. 30c. —— The Archeologic History of the State of New York. In press. Miscellaneous. 62 Merrill, F. J. H. Directory of Natural History Museums in United States and Canada. 236p. Apr. 1903. 30c. 66 Ellis, Mary. Index to Publications of the New York State Natural History cael and New York State Museum 1837-1902. 418p. June 1903. 75¢, cloth. New York State Defense Council Bulletin No. 1. Report on the Pyrite and Pyrrhotite Veins in Jefferson and St Lawrence Counties, New York, by A. F. Buddington. p.4o, il. Nov. 1917. Free. New York State Defense Council Bulletin No. 2. The Zince-Pyrite Deposits of the Edwards District, New York, by David H. Newland. p.72, il. Nov. 1917. Free. Museum memoirs 1889-date. 4to. 1 Beecher, C. E. & Clarke, J. M. Development of Some Silurian Brachiopoda. g6p. 8pl. Oct. 1889. $1. 2 Hall, James & Clarke, J. M. Paleozoic Reticulate Sponges. 350p. il. 7opl. 1898. $2, cloth. 3 Clarke, J. M. The Oriskany Fauna of Becraft Mountain, Columbia Co., N. Y. 128p. gpl. Oct. 1900. 8oc. 4 Peck, C. H. N. Y. Edible Fungi, 1895-99. 106p. 25pl. Nov. 1900. 75c This includes revised descriptions and illustrations of fungi reported in the 49th, 51st and 52d reports of the State Botanist. 5 Clarke, J. M. & Ruedemann, Rudolf. Guelph Formation and Fauna of New York State. 196p. 2tIpl. July 1903. $1.50, cloth. REPORT OF THE DIRECTOR IQIQ I4t 6 Ae M. Naples Fauna in Western New York. 268p. 26pl. map. 1904. 2, cloth. 7 Ruedemann, Rudolf. Graptolites of New York. Pt 1 Graptolites of the Lower Beds. 350p. 17pl. Feb. 1905. $1.50, cloth. 8 Felt, E. P. Insects Affecting Park and Woodland Trees. v. I. 46op. il. 48pl. Feb. 1906. $2.50, cloth; v. 2. 548p. il. 22pl. Feb. 1907. $2, cloth. $4 for the two volumes. 9 Clarke, J. M. Early Devonic of New York and Eastern North America. Ptr. 366p. il. 7opl.5 maps. Mar. 1908. $2.50, cloth; Pt 2. 25opl. il. 36p. 4maps. Sept. 1909. $2, cloth. to Eastman, C. R. The Devonic Fishes of the New York Formations. 236p. 15pl. 1907. $1.25, cloth. rr Ruedemann, Rudolf. Graptolites of New York. Pt 2 Graptolites of the Higher Beds. 584p. il. 31pl. 2 tab. Apr. 1908. $2.50, cloth. 12 Eaton, E. H. Birds of New York. v. I. 5oip. il. 42pl. Apr. 1910. Out of print, v. 2, 719p. il. 64pl. July 1914. Out of print. 106 colored plates in portfolio $1. 13 See H. P. Calcites of New York. tgop. il. 27pl. Oct. 1910. $1, cloth. 14 Clarke, J. M. & Ruedemann, Rudolf. The Euryperida of New York. v. I Text. 44op. il. v. 2. Plates. 3188p. 88pl. Dec. 1912. $4, cloth. 15 House, Homer D. Wild Flowers of New York. v.1.185p. 143pl. il; v. 2. 177 p. 12Ipl. il. 1918. $7 for the two volumes. Goldring, W. Monograph of the Devonian Crinoids of New York. Prepared. Pilsbry, H. L. Monograph of the Land and Fresh Water Mollusca of the State of New York. In preparation. Natural History of New York. 30 v. il. pl. maps. 4to. Albany 1842-94. DIVISION I zOOLOGY. De Kay, James E. Zoology of New York; or, The New York Fauna; comprising detailed descriptions of all the animals hitherto observed within the State of New York with brief notices of those occasionally found near its borders, and accompanied by appropriate illustrations. 5v. il. pl. maps. sq. 4to. Albany 1842-44. Out of print. Historical introduction to the series by Gov. W. H. Seward. 178p. v. 1 ptr Mammalia. 131 + 46p. 33pl. 1842. 300 copies with hand-colored plates. v.2pt2Birds. 12+ 380p. r4tpl. 1844. Colored plates. v. 3 pt 3 Reptiles and Amphibia. 7 + 98p. pt4 Fishes. 15 + 415p. 1842. pt 3-4 bound together. Vv. 4, Plates to accompany v. 3. Reptiles and Amphibia. 23pl. Fishes 7opl. 1842. 300 copies with hand-colored plates. v.5 pt 5 Mollusca. 4+ 271p. 4opl. pt 6 Crustacea. 7op.13pl. 1843-44. Hand-colored plates; pt 5-6 bound together. DIVISION 2 BOTANY. Torrey, John. Flora of the State of New York; com- prising full descriptions of all the indigenous and naturalized plants hitherto discovered in the State, with remarks on their economical and medical prop- erties. 2v. il. pl. sq. 4to. Albany 1843. Out of print. v. I Flora of the State of New York. 12 + 484p. 72pl. 1843. 300 copies with hand-colored plates. y. 2 Flora of the State of New York. 572p. 89pl. 1843. 300 copies with hand-colored plates. DIVISION 3 MINERALOGY. Beck, Lewis C. Mineralogy of New York; com- prising detailed descriptions of the minerals hitherto found in the State of New York, and notices of their uses in the arts and agriculture. il. pl. sq. 4to. Albany 1842. Out of print. 142 ' NEW YORK STATE MUSEUM v. I pt 1 Economical Mineralogy. pt 2 Descriptive Mineralogy. 24 + 536p. 1842. 8 plates additional to those printed as part of the text. DIVISION 4 GEOLOGY. Mather, W. W.; Emmons, Ebenezer; Vanuxem, Lardner & Hall, James. Geology of New York. qv. il. pl. sq. 4to. Albany 1842-43. Out of print. ‘vy. I pt 1 Mather, W. W. First Geological District. 37 + 653p. 46pl. 1843. v. 2 pt 2 Emmons, Ebenezer. Second Geological District. 10 + 437p. 1I7pl. 1842. v. 3 pt 3 Vanuxem, Lardner. Third Geological District. 306p. 1842. v. 4 pt 4 Hall, James. Fourth Geological District. 22 + 683p. I9pl. map. 1843. DIVISION 5, AGRICULTURE. Emmons, Ebenezer. Agriculture of New York; comprising an account of the classification, composition and distribution of the soils and rocks and the natural waters of the different geological formations, together with a condensed view of the meteorology and agricultural productions of the State. 5v. il. pl. sq. 4to. Albany 1846-54. Out of print. v. 1 Soils of the State, Their Composition and Distribution. 11 + 37Ip. 2Ipl. 1846. v. 2 Analysis of Soils, Plants, Cereals etc. 8 + 343 + 46p. 4eapl. 1849. With hand-colored plates. v. 3 Fruits etc. 8 + 340p. 1851. v. 4 Plates to accompany v. 3. 9g5pl. 1851. Hand-colored. v. 5 Insects Injurious to Agriculture. 8 -+ 272p. s5opl. 1854. With hand-colored plates. DIVISION 6 PALEONTOLOGY. Hall, James. Paleontology of New York. 8v. il. pl. sq. 4to. Albany 1847-94. Bound in cloth. v. I Organic Remains of the Lower Division of the New York System. 23 + 338p. g9pl. 1847. Out of print. v. 2 Organic Remains of Lower Middle Division of the New York System. 8 + 362p. tr1o4pl. 1852. Out of print. v. 3 Organic Remains of the Lower Helderberg Group and the Oriskany Sand- stone. pti, text. 12 + 532p. 1859. [$3.50] pt2. 142 pl.1861. [$2.50] v. 4 Fossil Brachiopoda of the Upper Helderberg, Hamilton, Portage and Che- mung Groups. II + 1+ 428p. 69pl. 1867. $2.50. v. 5 pt 1 Lamellibranchiata 1. Monomyaria of the Upper Helderberg, Hamilton and Chemung Groups. 18 + 268p. 45pl. 1884. $2.50. Lamellibranchiata 2. Dimyariaof the Upper Helderberg, Hamilton, Portage and Chemung Groups. 62 + 293p. 51pl. 1885. $2.50. pt 2 Gasteropoda, Pteropoda and Cephalopoda of the Upper Helderberg, Hamilton, Portage and Chemung Groups. 2v. 1879. v.I, text. I5 + 492p.; v. 2. 120pl. $2.50 for 2 v. —— & Simpson, George B. v. 6 Corals and Bryozoa of the Lower and Upper Helderberg and Hamilton Groups. 24+ 298p.67pl. 1887. $2.50. —— & Clarke, John M. v. 7 Trilobites and Other Crustacea of the Oriskany, Upper Helderberg, Hamilton, Portage, Chemung and Catskill Groups. 64 + 236p. 46pl. 1888. Cont. supplement to v. 5, pt 2. Pteropoda, Cephalopoda and Annelida. 42p. 18pl. 1888. $2.50. & Clarke, John M. v. 8 pt 1. Introduction to the Study of the Genera of the Paleozoic Brachiopoda. 16 + 367p. 44pl. 1892. $2.50. & Clarke, John M. v. 8 pt 2 Paleozoic Brachiopoda. 16 + 394p. 64pl. 1894. $2.50. Out of print. —_—— Catalogue of the Cabinet of Natural History of the State of New York and of the Historical and Antiquarian Collection annexed thereto. 242p. 8vo. 1853. REPORT OF THE DIRECTOR IQIQ 143 Handbooks 1893-date. j New York State Museum, 52p. il. 1902. Out of print. Outlines history and work of the museum with list of staff 1902. Paleontology. 12p. 1899. Out of print. Brief outline of State Museum work in paleontology under heads: Definition; Relation to biology; Relation to stratigraphy: History of paleontology in New York. Guide to Excursions in the Fossiliferous Rocks of New York. 124p. 1899. Out of print. Itineraries of 32 trips covering nearly the entire series of Paleozoic rocks, prepared specially for the use of teachers and students desiring to acquaint themselves more intimately with the classic rocks of this State. Entomology. 16p. 1899. Out of print. — Economic Geology. 44p. 1904. Out of print. Insecticides and Fungicides. 20p. 1909. Free. : Classification of New York Series of Geologic Formations. 32p. 1903. Out of print. Revised edition. 96p. 1912. Free. Guides Pie to the Mineral Collections, prepared by Herbert P. Whitlock. p. 45. 1916. Guide to the Collections of General Geology and Economic Geology, prepared by Robert W. Jones, p. 31. 1917. Free. Guide to the Paleontological Collections, prepared by Rudolf Ruedemann. p. 35, il. 1916. Free. Geologic maps. Merrill, F. J. H. Economic and Geologic Map of the State of New York; issued as part of Museum Bulletin 15 and 48th Museum Report, v.I. 59x 67cm.. 1894. Scale 14 milesto1inch. 15c. Map of the State of New York Showing the Location of Quarries of Stone Used for Building and Road Metal. 1897. Out of print. Map of the State of New York Showing the Distribution of the Rocks Most Useful for Road Metal. 1897. Out of print. Geologic Map of New York. Igor. Scale 5 milestorinch. Jn atlas form, $2. Lower Hudson sheet 5oc. Separate sheets of this map are available at 50c each, as follows: Ontario West Finger Lakes Delaware Niagara Long Island Adirondack South Western - §t Lawrence Hudson Mohawk Ontario East Central Lower Hudson (Note) The Ontario West is not colored as it has no surface geology. The lower Hudson sheet, geologically colored, comprises Rockland, Orange, Dutchess, Putnam, Westchester, New York, Richmond, Kings, Queens and Nassau counties, and parts of Sullivan, Ulster and Suffolk counties; also northeastern New Jersey and part of western Connecticut. —— Map of New York Showing the Surface Configuration and Water Sheds. 1901. Scale 12 miles to I inch. I 5c. —— Map of the State of New York Showing the Location of Its Economic Deposits. 1904. Scale 12 milestotinch. 15c. Geologic c¢ maps on the United States Geological Survey topographic base. Scale Iin.==1m. Those marked with an asterisk have also been published separately. Albany county. 1898. Out of print. Area around Lake Placid. 1898. Vicinity of Frankfort Hill [parts of Herkimer and Oneida counties]. 1899. Rockland county. 1899. Amsterdam quadrangle. 1900. *Parts of Albany and Rensselaer counties. 1901. Out of print. *Niagara river. IQOI. 25¢c. Part of Clinton county. Igol. Oyster Bay and Hempstead quadrangles on Long Island. 1go1. Portions of Clinton and Essex counties. 1902. Part of town of Northumberland, Saratoga co. 1903. Union Springs, Cayuga county and vicinity. 1903. 144 NEW YORK STATE MUSEUM *Olean quadrangle. 1903. Free. *Becraft Mt with 2 sheets of sections. (Scale 1in. 34m.) 1903. 20c. *Canandaigua-Naples quadrangles. 1904. 20c. *Little Falls quadrangle. 1905. Free. *Watkins-Elmira quadrangles. 1905. 20c. *Tully quadrangle. 1905. Out of print. *Salamanca quadrangle. 1905. Out of print. *Mooers quadrangle. 1905. Free. Paradox Lake quadrangle. 1905. *Buffalo quadrangle. 1906. Out of print. *Penn Yan-Hammondsport quadrangles. 1906. 20c. *Rochester and Ontario Beach quadrangles. 1907. 20c. *Long Lake quadrangle. 1907. Out of print. *Nunda-Portage quadrangles. 1908. 20c. *Remsen quadrangle. 1908. Free. *Geneva-Ovid quadrangles. 1909. 20c. *Port Leyden quadrangle. 1910. Free. *Auburn-Genoa quadrangles. 1910. 20c. *Elizabethtown and Port Henry quadrangles. 1910. 1I5¢c. *Alexandria Bay quadrangle. 1910. Free. *Cape Vincent quadrangle. 1910. Free. *Clayton quadrangle. 1910. Free. *Grindstone quadrangle. 1910. Free. *Theresa quadrangle. 1910. Out of print. *Poughkeepsie quadrangle. I9I1I. Free. “Honeoye-Wayland quadrangles. I9II. 20c. *Broadalbin quadrangle. 1911. Free. *Schenectady quadrangle. Ig11. Free. *Saratoga-Schuylerville quadrangles. 1914. 20c. *North Creek quadrangle. 1914. Free. “Syracuse quadrangle. 1914. Free. *Attica-Depew quadrangles. I9I14. 20c. *Lake Pleasant quadrangle. 1916. Free. “Saratoga quadrangle. 1916. Free. *Canton quadrangle. 1916. Free. “Brier Hill, Ogdensburg and Red Mills quadrangles. 1916. 15c. *Blue Mountain quadrangle. 1916. Free. *Glens Falls, Saratoga, Schuylerville, Schenectady and Cohoes quadrangles. I9QI7. 20c. Lake Placid quadrangle. 1919. Schroon Lake quadrangle. 1919. Cohoes quadrangle. 1920. Canton quadrangle. 1920. INDEX Accessions to collections, 32-38 Adirondacks, geology, 8 Albany county, postglacial deposits and drainage, 8 Alburg shale, 114 Alling, Harold L., work of, 8, 9 Archeological Association, 14 Archeological excavations on Bough- ton Hill, 11-13 Archeology, report on, 28-29 Ausable quadrangle, & " ! ata dake | eae, Bagg, Rufus M., work of, 9 Beauchamp, Wiiliam M.,.Cornplanter medal bestowed on, 14 Berkey, Charles P., work of, 8 _Bonaventure cherts, 9 Botany, report on, 17-18 Boughton Hill, archeological excava- tions, II-13 Buddington, A. F., work of, 8 Burmaster, Everett R., work of, 11 Canajoharie faunas, additions, 101-8 Canajoharie shale, 111, 122-24, 130 Caryocaris salter, 95-100 Cephalopods, fossil, on sex distinction in, 68 Chamberlin, T. C., cited, 47 Clinton formation and fauna, 8 Codling moth, 22-23 Colony, R. J., work of, 8 Cook, David B., work of, 13 Cook, John H., work of, 8 Corn insects, 20 Cornplanter medal, 14 Crinoids, Devonian, monograph, 9 Crop pests, 22 Cushing, H. P., work of, 8 Deep kill shale, 118 Devonian crinoids, monograph, 9 Dewey, Alvin H., Cornplanter medal bestowed on, 14 Dolgeville beds, fauna, 100-1 Dystactospongia radicosa nov., IO0I-3 Entomology, report on, 18-26 Essex county, postglacial deposits and drainage, 8 Ethnology, report on, 28-29 European corn borer, 18-20 Eurypterid, a new Eurypterid from the Devonian of New York, 88- 92; preservation of alimentary canal in an, 92-95 Eusarcus newlini, 92 Fairchild, H. L., work of, 8; cited, 47, 48, 56 Ferns and flowering plants of New York State, 17 Forest insects, 2 Fossil plants, 9 Fossil trees of Schoharie county, Q-II Gall insects, 24 Gall midges, 24 Geology, report on, 8; accessions, 32 Glossograptus quadrimucronatus, 63 Goldring, W., work of, 9 Gouverneur quadrangle, 8 Grain pests, 21-22 Graptolite zones of the Ordovician shale belt of New York, 116-30 Graptolites, homoeomorphic develop- ment, 63-68 Hartnagel, Chris A., work of, 8, II Horticultural inspection, 26 Indian Commission, activities, 14-15, Indian Welfare Society, 16 Tron ores, 8 Kemp, James F., work of, 8 Kokenospira rara nov., 106-7 Lake Bonaparte quadrangle, 8 Lake Champlain region, age of the black shales, 108-16 Lorraine beds, 123, 125 Lorraine fauna, investigations of, 8 [145] 146 Magog shale, 122-24 Miller, William J., work of, 8 Mineral industry, 8 Mineralogy, accessions, 37-38 Mollusca, living, 16 Mount Marcy quadrangle, 8 New York Indian Welfare Society, 16 New York State Archeological Asso- ciation, 14 New York State Indian Commission, activities, 14-15 Newland, David H., work of, 8 Normanskill shale, 117-18 Oncoceras pupaeforme noyv., 69 Onondaga limestone, 9 Orthoceras, color bands in, 79-88 Paleobotany, 9 Paleontologic contributions from the New York State Museum, 63-130 Paleontology, report on, 8; accessions, 32-37 Parker, Arthur C., Cornplanter medal bestowed on, 14 Potash, 8 Pterygotus inexpectans nov., 89, 90-92 Rice, Marion, work of, 8 Ruedemann, Rudolf, work of, 8, 11; Paleontologic contributions from the New York State Museum, 63-130 Russell quadrangle, 8 Salaries, inadequate, 7 Salt deposits, 8 Saratoga region, postglacial deposits and drainage,8 Schaghticoke shale, 118-22 Schenectady beds, 123 NEW YORK STATE MUSEUM Schizambon albaniensis noy., 105-6 Schoharie county, fossil trees, 9-11 Scientific papers, 39-130 Shade tree insects, 23 Shales, age of the black shales of the Lake Champlain region, 108-16; graptolite zones, 116-30 Snake Hill faunas, additions to, 101-8 Snake Hill shales, 123, 130 Staff of Department of Science, 29-31 Stevens, George E., work of, 13 Stoller, James H., work of, 8 Susquehanna valley, evolution of, 8 Tarr, R: S., cited, 47 Tetranota bidorsata, 106 Thompson, Mrs F. F., Boughton Hill site secured by favor of, 13; Corn- | planter medal bestowed on, 14 Trematis punctostriata var. minor nov., 103-4 Trematis terminalis, 104 Trilobites, on some cases of reversion in, 70-79 Triplecia nucleus, 104-5 Tully glacial series, 39-62 Utica shale, 115, 124-26, 130 Vanuxem, L.,, cited, 46 Victor, archeological on Boughton Hill, 11 Von Engeln, O. D., Tully glacial series, 39-62 excavations West Point quadrangle, 8 Wild Flowers of New York, pub- lished, 16 Woodward, Herbert S., work of, 11 Zoology, report on, 26-28 pitei Noealiee 27, 1915, at the Post Office at Albany, Novas remade 2 Aseswiaace. for mailing at special rate of bots provided for , is : a “ ALBANY, N. Y. JANUARY-FEBRUARY 1920 _ University of the State of New York ais eat New-York State Museum | ae Bet a9 ~ Joun. M. Care, ‘Director , "GEOLOGY OF THE MOUNT MARCY ee. ADRANGLE, ESSEX COUNTY, NEW YORK = > Y shh nstings eso % a ; BY att ‘on™ tr ) 2 “: bien: ~~ JAMES F. KEM cy 4 st 8 ae Seabee: a FER £01 022 Es Matianay th Aue” “WITH A CHAPTER ca Z on THE ce GEOLOGY BY HAROLD L. ALLING DA N IBUTION ON THE REACTION-RIMS OF ANORTHOSITES | Pes on _=BY ‘MAX ROESLER a < ie a _ ALBANY ROR eet. Te /. SSE ah Tame THE _ UNIVERSITY OF THE STATE “OF NEW YORK ‘a A: Fes . ‘1921 ze sic ¢ ; | r ; e 2 Bie Tee LUA) Sg ee et oe ee ta i 4 - . ” Pe . 5 , > Doe THE UNIVERSITY OF THE STATE OF NEW YORK Regents of the University With years when terms expire Revised to November I5, 1921 1926 Priny T.SExTon LL.B. LL.D. Chancellor Emeritus Painyrees 1922 CuEsTER S. Lorp M.A. LL.D. Chancellor — - Brooklyn — 1924 ADELBERT Moot LL.D. Vice Chancellor - -— — Buffalo 1927 ALBERT VANDER VEER M.D. M.A. Ph.D. LL.D. Albany 1925 CuaRLes B. ALEXANDER M.A. LL.B. LL.D. | Litt.D. Sy sss -. + =(Tuxedg 1928 WALTER cae Rte B. x LLD. - — Ogdensburg 1932 JAMES Byrne B.A. LL.B. LL.D. - - - — New York — 1929 HERBERT L. BripcmMan M.A.LL.D. - -— - - Brooklyn HOT LOMAS. MANGAN MLAS 6 os) S's ee Binghamton ¥ 1933 WILLIAM J. WattiIn M.A. - - - -— — — Yonkers 4 1923 Witt1AM Bonpy M.A. LL.B. Ph.D. - - - -—- NewYork 1930 WiLi1aM P, Baker B.L. Litt.D.- - - - —- Syracuse a President of the University and Commissioner of Education Frank P. Graves Ph.D. Litt.D. L.H.D.. LEED Deputy Commissioner and Counsel FRANK B. GILBERT B.A. LL.D. Assistant Commissioner and Director of Professional Education Avucustus S. Downinc M.A. Pd.D. L.H.D. LL.D. Assistant Commissioner for Secondary Education | CuarLes F. WHEELOCK -B.S. Pd.D. LL.D. Assistant Commissioner for Elementary Education Hae Grorce M. Wirey M.A. Pd.D. LL.D. Director of State Library - . James I. Wyer M.L.S. Pd.D. Director of Science and State Museum Joun M. Crarxe D.Sc. LL.D. Chiefs and Directors of Divisions Administration, Hiram C. CasE Archives and History, JAMES SuLtivAN M.A. Ph.D. Attendance, James D. SULLIVAN Examinations and Inspections, AVERY W. SKINNER B.A. Law, FRANK B. GitBert B.A. LL.D., Counsel - Library Extension, WILLIAM R. Wirson Bis: Library School, Epna .M. Sanperson B.A. B.L.S. School Buildings and Grounds, Frank H. Woop M.A. School Libraries, SHERMAN WILLIAMS Pd.D. Visual Instruction, ALFRED W. ABrams Ph.B. vo and Extension Education, Lewis A. WILson The University of the State of New York Science Department, September 30, 1920 Dr John H. Finley President of the University SIR : _I beg to communicate herewith and to recommend for publication as a bulletin of the State Museum, a manuscript entitled The Geology of the Mount Marcy Quadrangic, which has been prepared at my request by Dr James F. Kemp. Respectfully yours Joun M. CrarKeE Director Approved for publication President of the Umversity syIOY syvsny jo Agysy [, asato0or) Aq ydessojoyd & WOTY “dUR}SIP s[ppIwW ol} UT Ue}UNOU ISOOPT PUB F}YSII dy} UO UTe}UNOW YJoIT, MES ‘}Jo] IY} UO st UIAJOD JUNOPT “9RY URIPUyT WOT} ‘soyR] s[qesny IT, I 981d : New York State Museum Bulletin Entered as second-class matter November 27, 1915, at the Post Office at Albany, New York, under the act of August 24, 1912. Acceptance for mail at special rate of postage pro- vided for in section 1103, act of October 3, 1917, authorized July 19, 1918 Published monthly by The University of the State of New York Nos. 229-230 ALBANY, N.Y. January-February, 1920 The University of the State of New York New York State Museum Joun M. CLARKE, Director _ GEOLOGY OF THE MOUNT MARCY QUAD- | RANGLE, ESSEX COUNTY, NEW YORK BY JAMES F. KEMP ee ee ee eee ee I INTRODUCTION AND PHYSIOGRAPHY The Mount Marcy quadrangle embraces the culmination of the Adirondacks. Of all this group of mountains the two summits which rise above 5000 feet are both within its confines and of the sixteen higher than 4000 feet, it contains fourteen. Excepting the high peaks of the White mountains, where there are five which exceed Mount Marcy, and Mount Mitchell with its neighbors in. North Carolina, this Adirondack dome-shaped summit stretches away toward the sky to a loftier point than do any other elevations ot North America east of the Black hills of South Dakota. Mount Marcy’s true altitude was long unappreciated. Situated ' in the heart of the wilderness it was scarcely known until a third of the last century had passed. First the Catskills and then White- face were considered the highest peaks of New York. Later when the iron ores at Lake Sanford brought the settlers into the region, Mounts Marcy and MacIntyre were appreciated at their true value. Marcy, we learn, was called “ Tahawus” or the “ cloud-splitter ” by the Indians and with all due respect to New York’s great gov- ernor, one can not restrain a feeling of regret that the poetical and © “expressive name of the savages could not have remained attached te the peak. The Mount Marcy quadrangle is situated between latitudes 44° and 44° 15 and between longitudes 73° 45’ and 74° west from Greenwich. It is the third one west from Lake Champlain, as the 6 NEW YORK STATE MUSEUM ‘ Elizabethtown next east of it and the Port Henry, on the lake shore, lie between. The Lake Placid sheet is north, the Santanoni west and the Schroon Lake south. The geology of the area of the Mount Marcy sheet has already been described in a preliminary way and with small scale maps, but since these little reconnaissance maps were issued, much more detailed field work has been done leading to the present report. ‘The geology of the Elizabethtown and Port Henry quadrangles is described in detail in Bulletin 138 by the present writer and Dr R. Ruedemann; and the Paradox Lake quad- rangle lying to the southeast is covered in a preliminary way by the maps and text of Bulletin 96 by Dr I. H. Ogilvie. The nearest quadrangle on the west which has been mapped is the Long Lake, whose geology is set forth by Prof. H. P. Cushing in Bulletin 115. On the south, the Schroon Lake quadrangle, has been mapped by Prof. W. ]. Miller in Bulletin 213-214. To the north is the Lake Placid sheet mapped by Prof. W. J. Miller, in Bulletin 211-2127 Physiography © In the broad features of its relief the quadrangle embraces a series of northeast and southwest mountainous ridges separated by rather narrow valleys. While these features appear from a study of the contour map, or better yet by observation of the country from some lofty summit, yet its most important depression, the Keene valley of the summer visitor, is almost due north and south, and the northwestern portion, containing the historic grave of John Brown, is practically a sandy and gravelly plateau on the 2000-foot contour. On the south, too, the valley of Elk lake, rather broad, open and flat, is continued almost due south down the course of \ Lhe Branch 1 The field work on which the present bulletin is based was begun in the summer of 1893 with Heinrich Ries as companion. Reconnaissance maps were prepared by townships on the basis of a county atlas, and were sub- mitted with brief descriptions to Prof. James Hall, then State Geologist. In 1897 after preliminary copies of the topographic sheet were available more detailed work was done under the auspices of the United States Geological Survey, which later turned over the results to the New York survey. Upon this latter work the writer was accompanied by Charles H. Fulton. Four shorter trips have been made into the Keene valley in the intervening years to clear up obscure points. Acknowledgments are due the United States Geological Survey and Messrs Ries and Fulton. In tIg14, 1915 and 1919 valuable aid was received from Harold L. Alling, at first a student at the University of Rochester and later at Columbia University hut a summer resident in the Keene valley. The results of Mr Alline’s studies of the Pleistocene lakes and deltas form a separate chapter toward the close of the bulletin. A second chapter on the reaction rims of garnets has been kindly contributed by Max Roesler, based on work begun under the writer’s direction at Columbia University and completed at Yale University, GEOLOGY OF MOUNT MARCY i Notwithstanding these exceptions the large features show the great northeast structural lines, characteristic of the eastern Adiron- - dacks and due, as one is forced to conclude, to a series of block faults, whose escarpments look away to the northwest and whose dropped sides were probably therefore in this direction. The faults have probably superimposed a later structure upon an older one, which is marked by the relatively broad and open and more mature north and south depressions.t The lowest point in the quadrangle is the one where, on the 800- foot contour, the East branch of the Ausable river flows north across the boundary. All the other streams, except the little Niagara brook in the southeast corner, leave the area at altitudes above 1700 feet. The Niagara is on the 1340-foot contour, where it passes to the south. The highest point is, as stated, the summit of Mount Marcy, 5344 feet. There is therefore an extreme vertical range of over 4500 feet. The gravelly plateau of North Elba, standing at 2000 feet and above, constitutes the most extended area of fairly flat character within the quadrangle. Nothing is known of the depth to bedrock in this portion but it may well be as much as 300 feet. The first rocky ledge revealed in the course of the West branch of the Ausable river in the Lake Placid quadrangle is over 4 miles north of the boundary of the sheet. The mountains are in many cases of dome-shaped outline as one approaches their tops. Mount Marcy itself is a striking illustration. From a distance it resembles an umbrella without the projecting rod. Mount MacIntyre is much the same (see plate 14). The ascent of neither presents any difficulties beyond the length of the walk from the nearest shelter. The Gothics, on the other hand, culminate in a sharp narrow ridge, and the same is true of McComb, Dix, Colvin and a few more. McComb has a little cone-shaped elevation or nipple, super- imposed upon the general ridge, and is therefore easily recognized _ from a distance. Nippletop mountain is another of the same out- line and is somewhat higher than McComb. Pitchoff mountain is a very steep and narrow ridge, between two faulted valleys, while by way of contrast Table Top mountain well justifies its name. Escarpments. There are several precipitous escarpments within the quadrangle. The west side of Niagara mountain, in the extreme 1jJ. F. Kemp, The Physiography of the Adirondacks, Popular Science Monthly, March 1906, p. 199. 8 NEW YORK STATE MUSEUM southeast corner, is well brought out by the contours. It is interesting to note the way in which the feeders of Niagara brook all come in from the western side. Escarpments hem in the lower Ausable lake on both sides. They also do the same but in less pronounced fashion for the Cascade lakes. The pass on the north- west side of Pitchoff mountain is precipitous on both sides and is impressive for this reason. ‘All these cliffs probably are on the lines of old faults and ail have doubtless been freshened up by the plucking action of the continental ice sheet. Drainage. The mountains of the quadrangle constitute a divide between the Hudson and the Lake Champlain systems of drainage. Niagara brook and the outlet of Elk lake pass into the Schroon river and thence to the Hudson. Boreas ponds are the sources of the Boreas river which goes to the Hudson direct. Avalanche lake just east of Mount MacIntyre is one of the ultimate sources of the Hudson itself. Its outlet through Lake Colden and the Flowed Lands is the Opalescent river, which with many feeders from the Mount Marcy group of mountains passes into Lake Sanford, on whose eastern shore are the famous bodies of titaniferous magnetite. North and southeast of Mount Dix are the sources of the Boquet river which passes through Elizabethtown and thence to Lake Champlain at Willsboro. All the other streams feed into the two branches of the Ausable river, which unite at Ausable Forks and traverse the famous chasm into Lake Champlain, south of Plattsburg. Except those portions of the streams which practically belong to the lakes or ponds, all are swift in current, with rather steep gradi- ents. In the small brooks are several cascades or waterfalls with a sufficient drop to afford very picturesque bits of scenery. In the larger streams but two cascades are worthy of comment. Both are on the East branch of the Ausable river; one, a mile and a half above Keene Center, and another just below the first. The river pours over rocky ledges in each instance, while elsewhere its course is usually over a bouldery bottom of drift. There is some ground for the inference that the rocky ledges mark postglacial portions of the channel, although no positive evidence in the way of borings is at hand of buried water courses running around the ledges. This subject is more fully treated toward the close of the bulletin in the chapter on the Pleistocene. The large valleys were undoubtedly existent and of approximately their present size in preglacial times, and the Jarge features of the topography were earlier blocked out, ‘9991 4SHSNY Ul Ueye], “sea onp Suryoo] AdiePy JUNOT, JO }wWUIMS dy} WoIF Mar Z eI “ADIL JUNOT St ouT[AYsS oy} uO yeod \soysty WL “OSETIA ple] {| Aye] FO Sjiys}NO 9y} WOT SUIeJUNOW! DY} O} YINOs sUuIyOOT “Eq[*{ YJicN fo neojeid ATJoAvIs oy € 931d GEOLOGY OF MOUNT MARCY 9 The ice sheet freshened up cliffs, removed the weathered and loose mantle of débris, and filled the depressions with drift. Upon this the postglacial streams have established themselves undoubtedly - following for the most part the old preglacial lines. This topic will be more fully discussed under Pleistocene geology. In the southeastern corner of the quadrangle the brooks manifest in an appreciable degree the “trellised drainage” which is much better shown in the neighboring Elizabethtown quadrangle. Lakes. The quadrangle is not rich in lakes as judged by the gen- eral standards of Adirondack areas. Yet several of the bodies of water present features of great scenic beauty and of much geologic interest. The best known are the Ausable lakes, a divided pair of long, narrow character, practically forming the source of the East branch of the Ausable river. They lie in a contracted fault valley with steep rocky sides. The valley is essentially a unit, but the lakes are separated by a mile of sand and gravel, obviously the alluvial fan and delta which Shanty brook has poured into the depression so as to separate into two what was originally one. The dividing flat of gravel and sand may have some foundation of morainal mate-_ rials, not now visible, but its most probable explanation is the rapid deposition of drift washed in by Shanty brook soon after the departure of the ice sheet and modified and leveled off by periods of high water in the two ponds. The flat acts as a dam for the upper lake, which stands over 30 feet higher than the lower one (see frontispiece). The relationships are somewhat similar in the Cascade lakes, formerly called Edwards ponds and still earlier Long pond. They lie in a long, narrow, fault valley, with precipitous rocky sides. They owe their twofold character to a mass of boulders, gravel and sand and are believed to be due to an avalanche in 1830. The materials have come from the mountain on the south side and hold the western lake about 7 feet higher than its mate. The barrier of the eastern lake is a mass of boulders and sand, reinforced by vegetation, as is shown in plate 5. Avalanche lake lies in a narrow fault valley along the eastern front of Mount MacIntyre. Its banks are so precipitous as to require a scramble for their passage. Like the other cases just cited, its waters are ponded back by a barrier of drift. ‘Chapel pond on the road to the southeast from Beedes (Ausable Club) is a very interesting case of a body of water confined by a 10 NEW YORK STATE MUSEUM long, narrow mass of drift, which now extends in a direction 2pproximately parallel with the valley itself. The ridge is broad enough for a highway, yet on the northern side flows a small brook 30 or 40 feet below the level of Chapel pond. There may have once been a morainal mass all across the valley into which on the north side the present brook has cut, by removing the finer sand and gravel and by caving down the coarser boulders. Yet as an observer walks or drives along the highway he or she has the striking experience of viewing a pond confined by a natural dam along whose foot flows a brook entirely distinct from the outlet of the pond itself. Elk lake, sometimes locally called Mud pond, lies in a broad, drift-filled valley and has swampy extensions. To a less degree the same is true of the Boreas ponds. Both have been enlarged by artificial dams, constructed years ago, so that with the release of the ponded waters logs could be floated down to the sawmills. The broad and open character of these two valleys, heading up as they do so quickly to divides a few miles to the north, is a peculiar feature. One would suspect the presence of the soft limestones of the Grenville series, yet in the visible ledges nothing but anortho- site has been discovered. Neither valley can well be the remnant of a large and now obliterated north and south drainage. It is by no means improbable that under the mantle of drift the old weath- ered limestones of the Grenville are hidden. Glacial terraces. The mountainous sides of the Keene valley, in common with the other valleys of the region, have a pronounced series of terraces, built of deltas, deposited in successive glacial lakes. The lakes were caused by barriers, presumably of ice, to the north and standing for extended periods at definite levels. Their heights have been determined by Harold L. Alling.’ 2 GENERAL STATEMENT OF GEOLOGICAL FORMATIONS The Grenville Series and Its Contact Zones The geological formations represented in the Mount Marcy quad- rangle embrace only those of Precambrian time (with the possible exception of some basaltic dikes) and of the Glacial epoch, The geological column is as follows: * See pages 70 and following, : ‘o[sueipend oy} JO T9UIOD ysvoyj1oU dU} puodaq ysnf ‘(aspoT ouvoiingy) asnopy{ Aai[IA\ PY} WorF ‘AaT[Va Yoorg suyof ay} dn Adstep_ JwnoyY pseMmo} MoaIA “eureioued Jomo] “YseuUOON JO pWWWNS 94} Wor ADIePY JUNOP_ PseMo} MorA “ewerIoued Jodd~Q os Sprosen --- aps sig-----—J Araeyy----- 4 Hy BAG === sporpshey: ---- -- S330 t wat] === Suoatsuiy Ree oe Some 5 i port Oe Lo) fs) 2 Z = + < i =f a al a) a 8 q s 0 8 an spy $p2]J1eG)--------- ‘UTeJUNOUL Youd JO uowdivose-iney oy} SI jYSstt oy} JW “OLQI Je Ipl[spur] oy} 0} onp oq 0} PaAodTjIq st YOIYAr ‘SOYR] OM} OY} UdaMjoq JdIIVq IY} ‘puNnOise10F eau IY} UI SuIMOYsS ‘ayP] opeose) (soddn) u1tsaqysom oy GEOLOGY OF MOUNT MARCY II | Moraines and eskers Late or Post- } Basaltic (Camptonite) dikes ordovician Basaltic (diabase) dikes ! Gabbro-syenite dikes Algoman | Gabbro A : | : ar \ Syenite-granite series | uses Whiteface type Precambrian ; L Anorthosites Marcy type | . | Crystalline limestones Grenville Quartzites series Paraschists L | Paragneisses General summary. The glacial drift either in its original and unsorted condition or else modified by the action of water is very general in its distribution. It appears in largest amount in the valleys. There are no Paleozoic exposures, so far as is known. -No positive indications of any beneath the drift have been observed but an extraordinary number of flat slabs of Potsdam is in the drift above the old Weston mine. There are a few basaltic dikes, but the number is not great. They are entirely unmetamorphosed and have clearly entered the wall rocks after the general meta- morphism. Whether they are Precambrian or later in age, it is impossible to state but their petrographic characters are in some instances like those of the pre-Potsdam series described by Prof. H. P. Cushing,* and in others like those of the Postordovician dikes described by the writer? and V. F. Marsters. The gabbro syenite dikes have been observed in only one or two places. The most interesting is on the shores of Avalanche lake where a powerful dike appears in the gulch between Avalanche moun- tain and Mount Colden. It cuts the anorthosite. Another has been observed in the northern entrance to Indian pass. We have no direct evidence of their ages except that they cut the anorthosites ; but inasmuch as they are closely related to the basic gabbros of the Elizabethtown quadrangle on the east, and the latter are believed to be later than the syenites, these dikes are also placed later. They have strong mineralogical affinities with the syenites. - The syenites have been chiefly observed in the northern central portion of the quadrangle, where they are profoundly involved 1QOn the Existence of Precambrian and Postordovician Trap Dikes in the Adirondacks. N. Y. Acad. Sci. Trans. 1896, 15 :248-52. 2Trap Dikes in the Lake Champlain Valley. Bulletin 107, U, S, Geol, Survey, I2 NEW YORK STATE MUSEUM with the anorthosites. From relationships which have been best worked out in the Long Lake quadrangle by Professor Cushing! and which show the syenites to be later, the same relation is believed to hold good in the Mount Marcy. The intermingling with anor- thosites is complicated as will be later set forth. The anorthosites cover far the largest portion of the quadrangle. Practically all the southern four-fifths consist of them. They are somewhat variable in composition, the dark silicates mounting up at times beyond the characteristic percentages of the typical anor- thosite. There were presumably two outbreaks; there may have been more. The anorthosites appear in large, massive exposures for the most part, but they also break through the Grenville sedi- ments and include fragments of the latter in a very complex way. They and the syenites have brought about some remarkable contact zones with the Grenville limestones. One of these contains deposits of iron ores. The Grenville series of sedimentary gneisses, limestones and rarer quartzites embraces the oldest rocks of all. They are limited so far as known to the northern portion of the Keene valley and the adjacent mountains. They constitute a thick series of east and west strike and steep dip. They are very ancient rocks and were metamorphosed before the intrusion of the anorthosite. These several groups will now be described in order beginning with the oldest. THE GRENVILLE SERIES The oldest rocks in the Mount Marcy quadrangle are a series of sedimentary gneisses and crystalline limestones to which it is now customary to apply the name Grenville. The name is adapted from Canadian usage where it was first given by Sir William Logan to strata of the above-mentioned character in the township of Gren- ville, Ontario. The name has been generally adopted in the Adiron- dack work, where the strata are now known to outcrop in almost every quadrangle. Their most extensive development is in areas away from the central eruptive masses and the completest description thus far issued is by Prof. H. P. Cushing? in his description of the region of the Thousand Islands. The Grenville series occupies a relatively small portion of the Mount Marcy quadrangle. Its best development is in the valley of the East branch of the Ausable river, for about 2 miles upstream, 1N. Y. State Museum Bul. 115, p. 481, 1907. 2N. Y. State Museum Bul. 145. ‘o] sueipend IOATI a[qesny oy} FO youerq jsey ‘ourpue Ue Ul poploy ‘sstous d][TAUDI4 ‘ 9Y} JO ospo usey}10U oy} Ie9u 9 3381d GEOLOGY OF MOUNT MARCY 13 that is, south from the northern edge of the quadrangle. It extends also laterally for about 2 miles east and west but is cut by intrusive masses of anorthosite and syenite. Indeed, except for the bottom of the valley of the river the relationships with the intrusives are much confused, both here and in the neighboring parts of the Lake Placid quadrangle in the north. The river itself has washed clean a series of ledges so as to afford an extraordinarily good series of exposures (see plate 6), but as soon as one climbs the hills on either side the anorthosites and syenites seem to have penetrated the Grenville in the most intricate manner, to have produced contact zones of unusual interest and to have given rise to some bodies of magnetite in the zones, which have been the object of mining in earlier years. The Grenville is also in evidence in a patch of limestone included in anorthosite opposite the hotel on the Cascade lakes and across the lakes from it. Apparently the Grenville limestone has been ' caught up in the anorthosite, and has been charged with beautiful green diopsides (coccolite) and small black garnets. Along the Cascade lakes on the northwest side, and in the pass on the north- west side of Pitchoff mountain we find again complex relations, but this time, as nearly as one can determine, the anorthosite is involved with members of the Syenite series of eruptives. These curious phenomena will be taken up under the syenites and anorthosites. A third area is in the extreme northwestern corner of the quad- rangle. A central area of limestone with wollastonite is surrounded by rusty gneisses and quartz-diopside rocks. The enormous thick- ness of sands, and gravels in this area prevent tracing the exposures east and south. The most easily and certainly recognizable of the Grenville strata are the crystalline limestones which appear in beds of varying thick- ness. They may be but I or 2 feet in section, or again may reach 20 or more feet. No great section, however, is free from included masses of silicates or of fragments of the wall-rock or of intrusive tongues torn off in the great compression to which the region has been subjected. The limestones themselves are rather coarsely crystalline in texture. When recrystallized they afford very coarsely crystalline calcite, with cleavage faces over a square inch in area. The faces are then usually striated with traces of the gliding plane parallel with minus R. The limestone is also impregnated with diopside crystals of the variety coccolite. Beautiful examples may 14 NEW YORK STATE MUSEUM be obtained opposite the hotel on the Cascade lakes. The yeliow- green of the diopside, the black of the associated garnet and the white matrix of calcite are in decided contrast. The exposure of limestone is limited and as the surrounding rocks are anorthosite, the diopsides and garnet are probably due to contact metamor- phism. Colored plates 7 and 8 drawn from microscopic slides illustrate the mingling of these minerals. For these and plates 11 and 12 the writer is indebted to his friend, F. K. Morris. The limestones show the effects of great pressure. The bent and contorted shapes of the included masses of silicates or of the tongues of basic rock apparently representing old dikes and apophyses indi- cate this feature in the strongest manner. Figure 1 is a sketch care- Concealed Sur . oo 2 —afee ene ails => s=s Pee “2 . ’ " ine 7 tme sTane 4.) = arias ye al el: 1% ’ 1 Eien o) Bt NY: Car Sd a OT “ io on - Las - Sketch of Grenville Limestone squeezed between Layers of Gneiss Fig. 1 Sketch of Grenville limestone squeezed between layers of gneiss fully made to scale of an exposure on the west bank of the Ausable river, and so near the line with the Lake Placid sheet that it is diffi- cult to decide within which quadrange it falls. The extremely crenu- lated edge is sufficiently exposed to convince the observer that the limestone was molded like dough. In the exposures at and near the pits of the iron mines formeriy worked one-fourth to one-half of a mile west of the Ausable river, the limestones are associated with beds of black, granular pyroxene and with included masses of this and of magnetite in such relations as to indicate contact zones in one small case from the neighboring anorthosite ; in the large instances from the syenite. They can best be described under the heading contact zones. The thickest ledge of limestone observed in the field is found near PLATE 7 Green diopside crystals, embedded in white ealcite. Grenville limestone included in anorthosite, Cascadeville. Actual field 0.25 inch or 6 mm, Drawn by F. K. Morris. PLATE 8 Green diopside or perhaps hedenbergite; red garnet and white calcite, from a contact zone of Grenville limestone, west bank of Ausable river, 14% miles south of north boundary of quadrangle. Actual field 0.25 inch or 6 mm. Drawn by F. K. Morris. GEOLOGY OF MOUNT MARCY 15 the northwestern corner of the quadrangle on the north side of an unnamed brook. The overlying rock is not shown. The gneisses. The limestones are associated with well-foliated gneisses, sometimes of light-colored acidic character, sometimes dark and basic. In these respects the exposures are closely similar to those in neighboring quadrangles. The chief contrasts in the large way are due to the great abundance of igneous rocks in the Mount Marcy area and to the contact effects which they have produced on the Grenville sediments. It is difficult in many cases to draw the line between regional and contact metamorphism and to be certain as to original composition and the effects of saturation and partial digestion of the sediments by the igneous masses. The gneisses are also in many cases such close parallels in mineralogy with the members of the syenite series, or else so intimately involved. with the syenites that one may be sometimes in doubt as to where the metamorphosed ancient clastics end and the syenites begin. The most acidic phase of the sediments is a rather finely granular aggregate of predominant quartz, with very subordinate plagioclase and a very little orthoclase. About one-eighth of the slide consists of irregular shreds of colorless pyroxene, presumably diopside. Plate g A illustrates the relations and relative amounts. The quartz, which makes up fully three-fourths of the slide, is plentifully sup- plied with minute needles of rutile. The specimen was found along the edge of the sheet and less than one-half of a mile northwest of Owls Head. It probably represents an old clastic sediment, asso- ciated with the limestones and originally a sandy, somewhat calcare- ous shale. It is similar to rocks described by Professor Cushing in Museum Bulletin 115, pages 504-8. A slide of another gneiss, appearing as one of many included blocks in the anorthosite at the foot of the last steep rise of Owls Head, revealed bands of pale green, granular pyroxene, in parallel arrangement with other bands of both twinned and untwinned feld- spar. The plagioclase has the extinctions of varieties somewhat more basic than the labradorite series. A few titanites and an occasional magnetic complete the mineralogy. The rock is illustrated in plate 9 B. It is reminiscent of inclusions already described from the Elizabethtown quadrangle next east (Museum Bulletin 138, pages 34-35) in which, however, quartz replaces the feldspar, here noted. These inclusions were of varying size, but in the case cited were of a foot or less in diameter. They were sharply angular and showed no corrosion or absorption. The foliation of the different inclusions ran in all directions. The phenomena are 16 NEW YORK STATE MUSEUM extremely significant in that they prove that the gneisses were metamorphosed before they were picked up by the anorthosite, and that this foliation, running as it does in all directions, is not the result of pressure after the blocks were caught in the intrusive. It leads one to infer the comparatively late date of the entrance of the anorthosite and the existence of a long period of time, marked by regional metamorphism before its appearance. These inclusions are also reminiscent of observations made in the preliminary work of 1893, as set forth in the Report of the State Geologist for 1893, pages 440, 468 and 469. Along the road run- ning northeast, past Chapel pond, and amid what was believed to be at the time universal anorthosites, a small ledge was found of a dense, fine-grained rock whose composition was shown by slides to be much the same as that of the famous Saxon granulites; that is, it consisted of quartz, orthoclase and garnets. Much sur- prise was felt at the time that such an unexpected exposure should appear. Undoubtedly it was one of the included masses of old Grenville sediments so large as not to expose its edges in the few feet visible. The inclusion is now exposed for many feet along a fault and crushed zone, used as a borrow pit for the highway. A curious additional phenomenon which was noted for several inclu- sions near Owls Head, larger than those mentioned above, was shown to the writer by the late Erastus Hale of Keene Center. Mr Hale was an experienced surveyor with the dipping needle. Around the edges of the inclusions there is at times very strong attraction for the dipping needle, reaching go°, but the amount changes within a few feet, from 90° positive to 90° negative. Apparently along the borders of the included blocks there must have been developed some small masses of strongly magnetic iron ore, even though we could not see them. At times the needle was influenced by their south polar ends, at times by their north polar. A gneiss was collected in the field on the hill just east of the East branch and one-half mile south of the northern edge of the sheet. It was encountered in ascending. from the undoubted Grenville of the river bottom and was believed at the time to be a metamorphosed sediment. In thin section it revealed greatly strained micro- perthitic orthoclase and microcline, with irregular shreds of brown hornblende and pale green or colorless pyroxene. A little magnetite also appears. The rock is illustrated in plate ro. The mineralogy is that of the syenites and the exposure may well represent an intrusive mass of this rock, which has penetrated the anorthosites in this area. In spite of a careful search decisive evi- A. Grenville gneiss, northeast of Owls Head. The clear, light or gray mineral is quartz. The dark mineral is chiefly diopside. Crossed nicols, actual field 0.1 inch or 2.5 min. B. Inclusion of Grenville gneiss in anorthosite, just south of Owls Head. The clear or pale gray minerals are _orthoclase or plagioclase. The darker well-cleaved min- eral of high relief is diopside. Crossed nicols, actual field 0.1 inch or 2.5 mm. a 4 . te ‘ is “f . J A. Supposed Grenville gneiss resembling syenite. Micro- perthite is the pale gray mineral with numerous inclusions. The clear white or gray mineral with cleavage cracks is orthoclase. The very dark mineral is chiefly hornblende, except where the rectangular cleavage reveals pyroxene. Crossed nicols, actual field 0.1 inch or 2.5 mm. Hb Hb B. Syenitic gneiss from north side of Pitchoff moun- tain, containing garnet (G), associated with pyroxene (Px), uralitic hornblende (Hb), feldspar (Fs), and a little quartz (Q). White light, actual field 0.08 inch or 2.0 mm, GEOLOGY OF MOUNT MARCY ; l7 dence, however, did not appear. One goes from one rock to the other across small valleys or gulches with fault escarpments. ‘The same types of rock are involved in the most intimate way in the - pass traversed by the old highway, northwest of Pitchoff mountain. They have been interpreted as syenites and are described as such under the syenites where the mineralogy is further discussed. A candid observer can not, however, disguise from himself the pos- sibility that old Grenville shales may, under extreme metamorphism, assume a mineralogical composition not appreciably different from the acidic phases of the syenite series. The basic, hornblendic phases of the Grenville are less prominent in the small areas of the Mount Marcy quadrangle than in the larger exposures of the Elizabethtown and Port Henry quadrangles already described in Museum Bulletin 138. Shaly limestones or extremely calcareous and more or less ferruginous shales could yield aggregates of hornblende, orthoclase, plagioclase, biotite and magnetite. The hornblendic rocks might also conceivably be tongues of intrusive basic syenite, crushed and sheared in the dynamic pro- cesses through which the area has passed. The peculiar green and doubtless soda-bearing pyroxene of the syenites would be a very peculiar and unusual mineral in metamorphosed sediments. Contact zones. The best contact zones thus far discovered in the eastern Adirondacks appear in the northern edge of the quad- rangle. While they vary somewhat among themselves they do present in one exposure and another very typical cases of these phenomena and some interesting variations on the general theme. They may be taken up from the simplest cases to the most complex. Cascadeville. Many years ago early observers noted that in the talus at the foot of the mountain southeast of the barrier between the two Cascade lakes, then known as Long pond, there appeared specimens of green diopside and associated minerals in bluish calcite. The fallen blocks can be easily traced to the parent ledge higher up on the mountainside. The simplest explanation of the relations of this limestone seems to be the following: It is a mass of Gren- ville limestone included in the anorthosite which constitutes Cascade mountain. The exposure of limestone at the Cascade lakes was well known to Prof. Ebenezer Emmons during his work on the second district of the State from 1835 to 1840. On pages 228, 229 of his valuable and interesting report he speaks of it as follows: Passing now to the northwest part of the county we find several beds of primitive limestone, under nearly the same conditions as in the southern and eastern parts, Long pond is one of the most interesting; it is in the 18 NEW VORK STATE MUSEUM south part of Keene,! about 8 miles southeast of the Elba Iron Works and 4 or 5 miles from Miller’s in the same town. This bed, or rather vein, was brought to light by a slide from the mountain which rises steeply from a small sheet of water known in the vicinity by the name Long pond. The vein is 20 to 40 feet wide, and occupies the highest part of the slide, being nearly half a mile from the pond. It rises out of the hypersthene rock in the form of an irregular vein or, more properly, mass. It has the usual characters, but as a whole is coarser. Some parts furnish a fine blue, cal- careous spar. A fact worth mentioning is that the blue portion is confined to the surface, while the deeper situated is pale green; but on exposure to the light the latter also becomes pale blue. This locality furnishes undoubted evidence that the limestone is an injected mass, or, in other words, a plutonic rock. The mineralogist will find in this place a nich locality of pyroxene in all its forms and varieties. In color it varies from the darkest green to nearly white. It is in fine, glossy crystals, in perfect forms, and easily obtained by blasting the limestone. Phosphate of lime in tolerable good crystals may also be obtained. Another mineral which resembles idocrase is quite common; it is in very small crystals, but it has not been particularly examined. The limestone furnishes no tourmaline or feldspar; it is apparently more in the character of a volcanic product, furnishing particularly those minerals which are associated with lavas, as the pyroxene, amphibole, phosphate of lime, idocrase etc., while in other places the same rock shows its analogy to granite by containing tourmaline, feldspar, scapolite etc. Where the primitive limestone furnishes the latter minerals, it is in beds more widely extended, or much larger than in the former case. It is well known to mineralogists that the narrow veins of granite are more bountiful in fine minerals than the rock itself, when it occurs as one of the principal masses over a widely extended territory; in fact, under the latter form it is emi- nently barren, except where it is traversed by veins of the same substance of a much later period than the principal rock. In addition to the above minerals, we have found large regular crystals of scapolite, some of which now remain attached to the rocks, and are eight inches in diameter. The mass of limestone at Long pond belongs to one of those kinds which must necessarily be quite limited in extent. It is bounded on two sides by the hypersthene rocks, and runs south in its ascent up the mountain above the slide, where it is concealed by soil, moss and the underbrush of the forest. The above quotation is of much interest, not alone because it applies to the limestone of the Cascade lakes, but because it sets forth Professor Emmons’s views on the igneous or intrusive char- acter of the Grenville limestones. The views are not so unreasonable 1The name Long pond was the original of the Cascade lakes. They are also called Edmond’s pond in Watson’s History of Essex County, p. 421, footnote, where it is stated that an avalanche in 1830 divided the old pond into two. Professor Emmons mistakenly uses south for north, an error that is very easy for one to make going from the southerly Hudson drainage to the northerly flowing rivers. The pond is in the northern part of Keene. GEOLOGY OF MOUNT MARCY 19 as they might at first appear. The limestones are so often molded like dough that they might easily convey to one not aware of their | plasticity the impression that they were intrusive. The phenomena of contact metamorphism cover all the other features and have become much better understood since Professor Emmons wrote. The diopside is of a beautiful yellowish green in section and some- what darker green in the hand specimen. As is so often the case with silicates included in limestone, it is rounded as if corroded. Only rarely can the semblance of a crystal face be detected. Coccolite would be the most appropriate name for it, and by. this term it has been usually described. The grains range up to one-fourth of an inch (6 mm) in diameter and exhibit the characteristic cleavage (see plate 7). They constitute about 60 per cent of the mass of some specimens of the rock. With them are associated a few scattered garnets of smaller size, black in the hand specimen, yellowish brown in thin section, and of rounded outlines. In the slide they are included in the diopside and have an isotropic core surrounded by a doubly refracting zone. The remainder of the rock is calcite. Through the kindness of Dr G. S. Rogers, at the time instructor in mineralogy at Columbia University, an analysis of the diopside has been prepared. The crystals were separated from the calcite and were washed in dilute HCl to remove the last traces of the carbonate. Molec. Ratios SiO. 51.84 864 TiO- 20 2 a 808 Al.O3 7.61 74 ) ) FeO; 1.75 .10 84 g | FeO 1.02 14 SAU | MnO ae) I \ Ne 864 MgO 11.30 285 Ae | CaO 25.80 6a 9) He-O+ 43 24 } 100.16 When recast we obtain Thus about three-fourths of the 2 CaOSiO. 53.36 per cent MgOSiO, 20.10 FeOSiO: I. 08 Mg0O.Al1.03.Si02 14.05 MgO.FeO:.SiOz 2.60 Quartz 6.24 SiO, .20 99.86 mineral is the diopside molecule. 20 NEW YORK STATE MUSEUM One can hardly avoid referring the development of these diopsides and garnets to the influence of the neighboring anorthosite. The mixture is indeed not unlike the original of the ophicalcites near . Port Henry (see Museum Bulletin 138, page 23), where, however, the mottled rock can not necessarily be referred to contact action. At Cascadeville there is no passage to serpentine, but the diopside is beautifully bright and fresh. Garnets have not yet been noted in the ophicalcite. The geological relations are such as to suggest contact effects for these two minerals, diopside and garnet, as they are the most frequent of the lime-silicates in the undoubted zones. Below the limestone the anorthosite is cut by several basaltic dikes and contains a small exposure of magnetite. Contacts near Owls Head. The Grenville limestones appear in a few ledges northwest from Owls Head peak just at the edge of the quadrangle. From one of these a rather fine-grained contact rock was gathered, which was almost as dense as ordinary horn- fels. Under the microscope it proved to be about 70 per cent golden brown garnet, 20 per cent emerald-green pyroxene, and nearly 10 per cent quartz. The slide presents beautifully colored minerals (see plate 11). There is also another mineral, of bright aggregate polarization, which looks much like sericite as derived from orthoclase. Anorthosite ledges are frequent in the vicinity but the immediate contacts were not visible. Contacts south of Keene Center. In the improvement of the highway along the east bank of the East branch of the Ausable river and immediately beneath the word “East” on the map, three- fourths of a mile south of its northern edge, a ledge was blasted out in the spring of 1910. The excavation brought to light a most interesting assemblage of contact minerals. The hand specimen at once revealed wollastonite and garnet, with diopside and calcite in moderately coarse aggregates. Under the microscope the same minerals appear with one or two others. Garnet in calcite is shown in plate 12. The wollastonite is broken by its cleavages into finely prismatic bundles, in the common sections, but when cut across shows the characteristic cross-sections. The garnet, while pink in the hand specimen, becomes pale yellow in the slide. It sometimes alters as shown in the accompanying sketches to some more highly refracting, almost opaque mineral in wormlike growths, which are included in the garnet itself (see plate 13 A). They resemble leucoxene more than any other mineral. The slides also contain quartz and the aggregate mineral mentioned above under the con- PLATE 11 Red garnet and green diopside, contact rock, northwest of Owls Head, presumably a metamorphosed limestone. The diopside is more abundant than usual. The white is quartz and the gray is probably sericite after orthoclase. White light, actual field 0.1 inch or 2.5 mm. Drawn by F. K. Morris. = Aynd | at BN I eae re ee a J Contact zone south of Keene Center. ght, actual field 0.1 inch or 2.5 mm. Red garnet in white calcite. White li Morris. Drawn by F. K. : GEOLOGY OF MOUNT MARCY 21 tacts near Owls Head, which looks like sericite and is believed te be it. Less abundant than either the garnet or the wollastonite in the specimens collected in pale green diopside. The following two analyses of the garnet-wollastonite rock were very kindly made for the writer by Dr G. S. Rogers. No. 1 is the contact rock, chiefly wollastonite and garnet, with a little calcite and diopside. A sample much richer in wollastonite is given under no. 2. No. 3, also made by Doctor Rogers, is of nearly pure garnet, from another place along the contact. The analysis yielded also MnO 0.18 not mentioned in the tabulation. I 2 3 SiO, 48.17 62.56 36.29 Al:Os 12.69 t 2.39 10.29 FeO; .84 15.05 FeO I.41 2.92 MgO .40 WoT, 45 CaO 34.06 28.07 32.85 Loss 1.78 3.85 1.84 Sum . 99.35 99.34 99.69 Grossularite 55.01 10.38 45.45 Andradite 2.58 47.75 Wollastonite 19.64 37.66 Quartz 12.48 34.32 Diopside - 4.75 8.44 Calcite ~ 4.00 8.73 Total 99.30 99.53 In the third analysis, the unassigned per cents are pyroxene, carbonates, water and titanic oxide. They can not be assigned with. out assumptions and are at best of small importance. The analyses show that the garnet in the first two cases is chiefly the lime-alumina variety, grossularite, and as the other silicates call for no bases beyond the customary amounts in earthy limestones it is quite possible that the original sediment was an earthy limestone which had been recrystallized by the action of the igneous rock without the necessary admixture of other substances from the magma. The substances which have been driven off would be carbonic acid from combination with the lime, magnesia and ferrous iron, and water from combination with the alumina as kaolinite, and with the ferric oxide as limonite. Possibly all the silica was not originally in the form of quartz, but might have been the partially hydrated form chert. If, however, we assume that the silica was all quartz, or chalcedony, and assign the other bases to the above com- 22 NEW YORK STATE MUSEUM pounds, we can recast the analysis and obtain an original limestone of the following composition: CaO 26.17 Calcite 46.66 MgO ey Magnesite .65 FeO T.08 Siderite 1.74 CO, 21.49 Kaolinite 24.69 AlOs 9.75 Limonite .74 Fe.O; 65 Quartz 2552 SiO, 37.02 H.0 3.53 100.00 100.00 The above composition is not an impossible one for an earthy rather siliceous limestone. Such a one might have existed and have become recrystallized with no contributions of matter from the igneous rock. It is by no means certain, however, that silica was not introduced. The third analysis with its large proportion of andradite resem- bles the usual run of garnets from contact zones. The composition can not well be explained without assuming the introduction of iron oxide and silica from the igneous mass. The contacts at the Weston mines. The most important of the contact effects are found to the west of the main valley of the Ausable river and reach their maximum one-half of a mile up a tributary stream which enters the Ausable from the northwest very near the edge of the sheet. The bodies of magnetite, which the contact zones contain, attracted attention as early as 1847. During the great period of activity of the bloomaries throughout the next 30 or 40 years when every water-power had its forge, its blowing engine, and trip hammer, mining operations were carried on to such a degree as to leave rather large excavations in two places, a num- ber of exploring pits in others, and dumps which give a good idea of the geological relations. The mining ceased in 1880 and the buildings have all fallen in ruin since. The best of the early records is that left by Bayard T. Putnam in volume 15 of the Tenth Census Reports, page 118. His words may be advantageously quoted in their entirety. The Hale mine is located at Long Pond mountain, about 1 mile southwest of the village of Keene, Keene township. It is worked by W. F. and S. H. Weston. The ore lies in white crystalline limestone. The first open- ing made in the vicinity is on the Wood farm, which adjoins the Hale farm on the west. The Wood mine was opened by the Westons in 1872, and was abandoned in December 1880. It produced 1120 tons of ore in the census year. The ore formed a shoot 8-16 feet wide, which dipped at a high angle to the northwest and pitched to the northeast at an average angle of Plate 13 A. Dark wormlike alteration products from and in the garnet of the contact zone south of Keene Center. Actual field 0.1 inch or 2.5 mm. White light. ‘ B. Many minute garnets in diopside. Contact zone south er ecne Center. Actual field 0.1 inch or 2.55 mm. White light. GEOLOGY OF MOUNT MARCY 23 45°. The pit is said to be between 250 and 300 feet deep (measured on the bottom rock of the shoot). Crystalline limestone surrounded the ore on all sides and was intimately mixed with it. From specimens seen limestone appeared to form the chief gangue. The Hale mine was opened in the spring of 1880. A shaft was sunk 50 feet through surface material and entered what appears to be a large body of ore lying nearly horizontally in the limestone. A chamber 51 feet square has been excavated. On the east the ore pinches out; on the west it is cut by a dike, which forms the west wall of the pit; on the north there is a breast of ore 8 to Io feet high. In places the room is 16 feet high, with ore still on the floor. Lying in the ore, are, however, layers of limestone of various thicknesses, so that this height does not represent the thickness of good ore. Not enough work has yet been done to determine definitely the shape of the ore-body; but the probabilities are that the chamber is on the top of a shoot of ore which pitches to the northward as in the Wood mine. Samples of the ore as it comes from the mine and after concentration contained : No. 1199 No. 1200 Metallic iron 49.37 59.92 Phosphorus absent 0.002 Titanic acid_ absent absent Phosphorus in 100 parts iron 0.000 0.003 Sample no. I199 is from 50 tons “primitive ore.’ Sample no. 1200 is from 100 tons of “separated” ore. The chief gangue is calcite. Pyrite seems to be absent. A brief additional note was published on the mines in 1889 by Prof. J. C. Smock, in Bulletin 7 of the State Museum, page 35, and some geological details, with a small section at the mines by the writer on the basis of observations made in 1893 (Report of the State Geologist for 1893, page 468). Not one of the observers cited was, however, impressed with the nature of the ore-bodies and their associations as contact effects. The experience of the last 10 years has been necessary to bring out these relations as they should be understood. We now realize that the ores conform to the characters lately established for many magnetite bodies and their associated lime-silicates. The exposures extend for one-fourth of a mile or more in general direction a little east of north. They are apparently surrounded on all sides except the brook valley leading to the Ausable river, by anorthosite. In the brook valley, syenites, or at least rocks believed ‘to be syenite appear. The anorthosite also penetrates the limestone series as the geological section later given will show. Drift is heavy and widespread, making some features a matter of inference rather than observation. On the north the first exposures appear in an open cut, driven across the measures in a westerly direction for 40 feet. The details are shown in figure 2. About 50 feet of limestone have been caught between two masses of anorthosite. The limestone has been 24 NEW YORK STATE MUSEUM changed into three different varieties of rock. In one 10 or I2 feet thick, it is charged with diopside; in the next about 1 5 feet it has become a black, granular pyroxene which doubtless encour- aged the search for ore; finally the last, about 20 feet thick, largely changed to garnet and pyroxene, with which apatite is found under the microscope. East Nee Yew ANORTHOSITE Geenae oe LIMESTONE AnorTHOSITE CHARGED WITH Py rRoxene Rock GRANULAR 0D 1OPSIDE Py ROXENE Fig. 2 Cross-section of north prospect, Weston mines, looking south. The strike is N 5 E unless compass was influenced by local attraction. One-eighth of a mile to the south one finds another large pit now so caved as to be inaccessible. Erastus Hale of Keene Center, with whom I visited it a second time, called it the “ Fifth shaft.” The inaccessible rocks had an apparent dip to the west. On the dump was much limestone, charged with pyroxene, lime-silicate hornfels, consisting of green pyroxene containing multitudes of little garnets. There is also a green rock consisting of diopside about 75 per cent and calcite 25 per cent. All these rocks are undoubted contact effects, and the magnetite which was mined and of which a few stray pieces are still available, was one of the char- acteristic attendant features. Li eta a renter r8 was tamer ksh me ee ean enema eee { i+, i yur Ad eee: ae mere) Fig. 3 Sketch of a fragment of Grenville gneiss, caught up in anorthosite. Near Fifth shaft, Weston mines. GEOLOGY OF MOUNT MARCY 25 Fifty yards above this pit and on the hillside anorthosite out- crops, in which is caught up a fragment of gneiss as shown in figure 3. It is one of many such cases in the vicinity of the Keene valley. One-fourth of a mile or less south of Fifth shaft is a large open cut some 75 feet long and 25 feet deep now caved in with only a few old timbers sticking through the drift. It is the abandoned Hale mine. The dump, however, shows the usual limestone charged with pyroxene, and the garnet-bearing hornfels. The largest workings of all at the old Weston or Wood mine are still farther south and in the valley of the brook which comes down from Cascade mountain. Only the old dumps and the walls of old stalls in which the ore was roasted now remain. Limestone charged with pyroxene, or with garnet, occasionally showing rude crystal outline, or with magnetite, indicate the old mineralogy. By amplifying the available material with the collections made in 1893, avery good idea of the relationships can be obtained. SYENITE )N THIS INTERVAL. Hy MILE £ OF = ft Wale o Ree Ee L xe = DG) Fr = ws Ge = nko sy Te u oz uw Bee ae he Ee 2“9 a“ = a va eo bao ° & a me is wu 2 2 © i o < Fig. 4 Cross-section near Weston mines, looking southeast Figure 4 is plotted from observations made in 1893, in the brook beginning with exposures to the southeast and passing upstream toward the mine. In the section the observer is looking at the south or southeast bank so that the eastern end is at the left. The gneiss first encountered varies somewhat in the slides, but the most import- ant mineral is microperthite in irregular shreds and torn fragments showing the results of crushing and severe pressure. In the first slide it is accompanied by shreds of emerald green augite and pink garnet. A very little quartz may be present, and a very little mag- 26 NEW YORK STATE MUSEUM netite and apatite. A tiny veinlet of quartz with a little calcite and a kaolinized selvage runs across the slide. The rock is roughly 50 per cent microperthite, and 24 per cent each garnet and augite; the others making up the remainder. It is probably a crushed member of the syenite series rather than an old Grenville gneiss. The next slide contains the same minerals with the addition of plagioclase, one crystal of the latter forming 10 per cent of the slide. The last slide shows no microperthite or augite, but is plagioclase of medium acidity and hornblende. This variation is within the limits of known changes in the syenitic rocks, and does not preclude the originals from being intrusive syenite of variable character. A short distance to the south of the mine another exposure of gneiss like the middle one described above was observed. The gneiss is succeeded by 25 feet of ophicalcite, and this by 15 feet of gneiss, which resembles green syenite. Nearly 50 feet was then concealed, followed by a gneissoid rock, from which a specimen on microscopic examination revealed an intimate inter- growth of golden brown garnet and bright green pyroxene. It is obviously a garnet contact zone and was probably once limestone. While generally in rounded or irregular polygonal intergrowths, there are some fingerlike interpenetrations. This rock continues for 200 feet or more and was eventually succeeded by ophicalcite or pyroxenic limestone containing the ore. Of the immediate asso- ciates of the ore one could only judge from the dump. Obviously garnets, pyroxene and calcite were mixed with it. For one-fourth of a mile farther to the westward in the bed of the brook green, syenitic gneiss, richly charged with garnets can be traced in occa- sional ledges. The huge boulders concentrated by the brook from the very heavy moraine which fills the valley then make up the bed for one-half of a mile or more. The brook is down in a gulch in glacial drift estimated at 150 feet in vertical depth, and the boulders range up to 15 or 20 feet in diameter. They are all anorthosite. Ultimately the brook takes its rise in the anorthosite of Cascade and Porter mountains. The nature of the green syenitic gneiss is obscure. It may be intrusive syenite, but if so is extra- ordinarily rich in garnet, a fact which might be explained by the absorption of Grenville calcareous sediments. The gneiss may belong to the Grenville, an interpretation which would seem to be favored by the association of the limestone. The abundant garnets might then be referred to the metamorphism of calcareous, sedi- mentary admixtures. The former interpretation is here given GEOLOGY OF MOUNT MARCY 27 preference and the exposures have been assigned as far as possible the syenitic color on the map. In the morainal deposit in the fields above the gulch of the brook, literally scores of slabs of Potsdam sandstone can be observed. They are flat and angular, just as if transported from a ledge a short distance away. No Potsdam has ever been found in place for many miles in all directions. The most reasonable interpretation of these observations on the ores would seem to be one involving the intrusive entrance of both the syenite and the anorthosite into the Grenville series and the production of the garnet diopside, contact zones. Coincidently came the development in several places of the bodies of magnetite, which were large enough to have furnished in the old days of the local forges commercial amounts of low phosphorus, low sulphur iron OTe. \, Contact on the west bank of the Ausable river. One and one- . half miles south of the north border of the quadrangle, and a short distance north of the bridge where the main highway from Keene valley to Elizabethtown crosses the river, is a very interesting, coarsely crystalline contact rock consisting of deep red garnets, black pyroxenes, which are a beautiful emerald green in thin sections, calcite and scapolite. The rock is illustrated in color plate 8 and in black and white plate 19A. ‘The pyroxene is probably the variety _hedenbergite, because while visibly pleochroic, green to yellowish green, it has a high extinction angle and can not be aegirite, as also remarked by Max Roesler in a contribution, later embodied in this bulletin. An extensive ledge of the garnet-pyroxene rock is exposed next the highway. Summary of the Grenville Series The preceding descriptions of the Grenville series will make clear that the ancient sediments are involved in a complicated way with the later intruded anorthosites and syenitic rocks. The lime- stones are our best preserved and recognizable originals but even they have given rise to contact zones and have been replaced with magnetite. The gneisses are chiefly microperthite-quartz rocks, ‘with some green diopside. They are much the same as some acidic phases of the syenite series, but on the whole are believed to be old Grenville beds which may have suffered changes from the influence of the intrusives. At least three separate times the writer has returned to study the outcrops, only to find them so complicated 28 NEW YORK STATE MUSEUM as to prevent a more sharply defined expression than this. Much the same conditions are met in the study of similar relationships in Sweden, where the writer in I9I0 in connection with the excursions of the Eleventh International Geological Congress had the oppor- tunity to observe similar phenomena and to discuss their relation- ships with the Swedish geologists. Explanations involving satura- tion with igneous matter, digestion and assimilation alone seem to make possible a reasonable conception of their complex develop- ment. In other areas of the Adirondacks and their borders similar conclusions regarding the complexity of the relations of the Gren- ville with the syenite have been reached. Prof. W. J. Miller describes and maps the “ Syenite-Grenville Complex ” (Bulletin 126 on the Remsen Quadrangle) where the intermingling was too intimate for separation. 3 THE PRECAMBRIAN INTRUSIVES WITH A CONTRIBUTION By MAX ROESLER ON THE REACTIONS RIMS The anorthosites are far the most abundant of all the rocks in the quadrangle. They are almost entirely made up of plagioclase feldspar, which itself is chiefly within the ranges of labradorite. The rocks were called “hypersthene rock” or “ hypersthene ” by Prof. Ebenezer Emmons," who, however, recognized both the illogi- cal practice of naming a rock after one of its subordinate minerals and also the varying mineralogy. In later years we have applied quite universally to these feldspar rocks the name anorthosite given by Dr T. Sterry Hunt in Canada in 1863. The name implies that the rocks consist essentially or predominantly of plagioclase. Hypers- thene is indeed a rather frequent dark silicate in the masses of labradorite, but we also find with the microscope, hornblende and augite, and we can frequently observe with the eye alone garnet and titaniferous magnetite. The anorthosites have been quite fully described in previous bulletins * of the State Museum, as the detailed mapping has proceeded. The anorthosites cover practically all but a small part of the Mount Marcy quadrangle. The area of the Grenville rocks and the Syenite series on the north alone extensively interrupt them. There are, however, in addition, some dark dikes of gabbro-syenite, aah ee ie Second District, p. 27-30, 1842. * H. P. Cushing, Bulletin on Long Lake Quadran les! r907. 1) JOB Bulletin 138, Elizabethtown and Port Henry Wnadmngiy side iin ureyunouL d}IsoyjIOUe PoapuNoI ‘dI}sI19}OvVIVYD BV ‘spue] PeMO][Y 9Y} SSO1OB jseay}NOS oY} WOIf PoMoIA oa1AjUTIVIY JUNOT VI 9381 GEOLOGY OF MOUNT MARCY 29 some basaltic dikes and also some curious included masses as will be later described. ; While the anorthosites are always predominantly plagioclase, they do contain varying amounts of dark silicates, which may become decidedly prominent features, especially on the borders of intrusive masses. They mark passages to the normal gabbros. In order to test the range in varieties of plagioclase by means of specific _gravities, a set of eleven specimens weighing from 10 to 40 grams was selected and the specific gravities were determined in distilled water with a chemical balance amid the usual physical conditions of a laboratory. It is impossible to get representatives entirely free from inclusions or slight admixtures of heavier minerals. The specific gravities which exceed those of anorthite are due to this admixture.* INEWICOMMD 65.0055... eek ul PROOZ NOt ElindSonmaiie.sa 4 aces 2.711 Bssexat se eae) SLOT TRRE PMOOS SS CUGO OM) yun als Oe ih eee ails 2.714 are ATE Ys: Woe o aapsings orients PeOOOuemealtityg | LOSEY . ass cum sicvebrnsccatale a 2.77, IMecne Valley... 6s. teense oss 2000 Elizabethtowim 72 4:.)...¢5420 55 2.736 Mate Plaids t \. AM A 7Oomuuocality Wosth 9 0 ea 2.770 Wocalttiagilostei ete. waa 2.803 It is evident that the greater number are a little below or a little above 2.700. The plagioclases range as follows: Albite Abi Ano 2.605 Labradorite Ab; Anz 2.710 Oligoclase Abs Ani 2.649 Bytownite Abi Ans 2.733 Andesine Abs Ani * 2.660 Anorthite Ab. Ani 2.765 Andesine-Labradorite transition Ab, Ani 2.679 Determinations of this sort are believed to be more comprehensive than observations of extinction angles in scattered thin sections. The anorthosite may therefore be considered predominantly or essen- tially labradorite. The component crystals are sometimes coarsely 1In the valuable paper “Notes on the Lithology of the Adirondacks,” 13th Annual Report, N. Y. State Museum, p. 86, 1876, the late Prof. Albert B. Leeds gives the specific gravities of forty-two specimens called norite, under which name the labradorite and other plagioclase rocks, chiefly from the Keene valley, are included. The values range from 2.67 through 3.24. An additional one of diallage at 3.386, and one of hvpersthene at 3.459 are given. Since anorthite, the most basic and heaviest of the feldspars is 2.765, all values above this (no. 11 in Doctor Leeds’s series) must have other heavier minerals. Analysis no. 1 of anorthosite as given two or three pages later from Doctor Leeds is no. 8 in his list, and analysis no. 2 is his no. 4. The percentages of other and heavier minerals than feldspars, as given in the results of recasting, will throw some light on the extent to which higher specific gravities call for pvroxenes, garnet, ilmenite and other heavier - minerals. Evidently basic sabbros or basic syenites as we now know the rocks, must be included in Doctor Leeds’s list. Unfortunately he gives the localities of only the two or three analyzed, so that we can not trace the others. 39 NEW YORK STATE MUSEUM tabular and are arranged with their flat sides parallel in a rude flow- ing arrangement. Under the microscope the labradorite presents broad crystals consisting of multiple twins. As is so often the case with rocks of the gabbro family, the labradorite is often charged with minute inclusions, such as small brown rods, blebs and un- identifiable dust. There seems no reason to doubt that as elsewhere these minute particles are fragments of pyroxene, spinels and ilmenite. The greatest difficulty in the accurate study of the anor- thosite lies in the widespread granulation to which it has been sub- jected. Exposures of perfectly crystallized rock are less frequently seen. They are best developed in the southwestern and southern portions of the quadrangle. Generally, however, the labradorite is crushed and granulated around a central nucleus which may survive. Stages can be traced from uncrushed originals, at times of very coarse texture, with components comparable to rather coarse pegma- tites ; through those whose feldspars have granulated edges ; through others in whose granulated mass only remnants of the original labradorite survive; to a final stage of complete granulation which has left a pulp of small fragments of labradorite. Coincident with the crushing the circulation of groundwaters seems to have taken place. In some specimens serious changes to scapolite and calcite have developed, producing the old-time aggre- gate called saussurite. The severe scraping, however, which the region has suffered from the continental ice sheet has tended to clean away the softer varieties, and leave only bright, fresh rock. The coarser varieties of the less granulated or ungranulated anor- thosites sometimes display the irridescent play of colors character- istic of labradorite, a feature that may be observed in the smooth bottoms of cascading brooks. Doubtless the name Opalescent river for the stream on the west slope of Mount Marcy was suggested by this feature. The anorthosite displays at times appreciable amounts of the bronze-colored, faintly irridescent hypersthene, which attracted the special attention of early observers. The hypersthene has irregular outlines and under the microscope reveals the usual features of the mineral. The chemical composition of a specimen from the summit of Mount Marcy was determined in 1875 or 1876 by the late Prof. Albert B. Leeds of Stevens Institute and is given in the valuable paper entitled ‘‘ Notes upon the Lithology of the Adirondacks,” * to which reference has already been made on an earlier page. 1 Thirtieth Annual Report of the New York State Museum, 1876, p. 79. The analysis of hypersthene is on page 25 of the repaged reprint. A. Uncrushed anorthosite showing the twinning of the labradorite. The original rock was almost black in color and was obtained at the southwest border of the quad- rangle, west of the Boreas ponds. Crossed nicols, actual field 0.1 inch or 2.5 mm. B. Part of a large augite crystal in the anorthosite, figure in A, above. White light, actual field 0.1 inch or 2.5 mm. GEOLOGY OF MOUNT MARCY 31 SiO Mol. aatis 102 50.33 .83 ) TiO, ‘O7 0008 § pees Al.Os 3.36 033 Fe:Os _ 1.03 Riis t -039 ts 19.40 Ban } n AGA . l= MeO 21.40 .O1O0 f 817 CaO 2.77 mee H.O 1.14 Gea 100.21 Obviously the mineral contained chiefly MgO,SiO., FeO,SiO,, with a little MnO,SiO,. Presumably the CaO was present in some monoclinic pyroxene or in some admixed labradorite, combined with the alumina and silica. The next dark silicate in relative importance, if indeed it does not exceed the hypersthene in actual frequency, is augite, which is emerald green in thin section. It is illustrated in plate 15B. Pre- sumably the same mineral is described by Professor Leeds under the name diallage, a name now much less used than formerly. His analysis follows. Mol. ratio SiO, 46.28 De A TOs 59 .007 778 Al.O: 738 .072 6 FeO; 2.21 .O14 FeO — 14.80 .206 682 MgO 8.91 .222 590 CaO 18.78 .168 } H:O I.1I5 100.065 It is evident from the molecular ratios that we have an excess of silica no matter what well-known pyroxenic molecules we assume. If we recast by assigning all the alumina to the anorthite molecule so as to use twice as many silicas, we are still confronted with an excess. There must have been some free silica in the sample in order to con- form with the percentages, or else some included feldspar with the albite molecule, whose soda was not determined. Hornblende has been occasionally noted in the anorthosites and biotite also. Biotite is not often seen in the Mount Marcy quad- rangle. It is far more abundant in the anorthosites of the south- eastern portion of the Ausable quadrangle. Titaniferous magnetite, the mechanical intergrowth of magnetite and ilmenite, is scattered at times through the anorthosites in association with the bunches of dark silicates. No great masses of it have been discovered in the 32 NEW YORK STATE MUSEUM Mount Marcy quadrangle comparable with those on Lake Sanford to the west, where it forms important bodies of ore. Three analyses are available of the anorthosite from lecalities within the Mount Marcy quadrangle. Two were made by Prof. Albert B. Leeds (1 and 2 below). The sample for 1 was the coarsely crystalline variety of uncrushed feldspar from the summit of Mount Marcy. No. 2 is the granulated variety and was regarded by Doctor Leeds as the ground mass of a porphyritic rock. The locality is not stated in his paper. No. 3 has been specially made for this bulletin by Dr C. A. Jott, at the time of the department of chemistry at Columbia University. The analysis was based on a large sample from the High Fall, Giant Trail. The rock was a more pyroxenic variety than the other two. : I 2 3 SiO, 54.47 54.62 52.37 Al.Os 20.45 26.50 24.68 Fe.O; 1.297 0.757 1.24 FeO 0.665 0.565 3.49 MgO 0.69 0.74 2.00 CaO 10.80 9.88 10.57 Na,O 4.37 4.50 4.02 K,0 0.92 ee 0.86 H.O+ 0.53 0.91 0.90 Total 100. 192 QQ. 702 100.13 Sp. grav. 2.72 27 not det. Quartz 1.62 1.56 Deficit .9O Orthoclase 5.004 7.23 5.00 Plagioclase 84.186 82.20 80.52 Magnetite 1.856 .93 1.62 Kaolinite 2.58 3.87 Water .15 sae .90 Diopside and hypersthene 4.616 4.30 12.86 Light-colored minerals 6.472 93.97 85.52 Dark-colored minerals 93.39 5.23 14.48 Plagioclase Abi Ans Abi Ano.s Abi Anse 1 Anorthosite, summit of Mount Marcy, A. B. Leeds, N. Y¥. State Mus. 30th Ann. Rep’t, 1878, p. 92. 2 Anorthosite, granulated variety. Probably Keene valley. A. B. Leeds, as under I. 3 Pyroxenic anorthosite, High Fall, Giant Trail, C. A. Joiiet, for this bulletin. Previously published in N. Y. State Mus. Bul. 138, p. 36, 1910. All these analyses show that the rock is nearly all labradorite, but that minor though variable amounts of the bisilicates and magnetite are associated. Doctor Leeds in discussing his two analyses develops the elaborate calculations which were practised by the mineralogists and petrographers of forty years ago, and which have become so much simplified in the years since then. GEOLOGY OF MOUNT MARCY 33 The anorthosites as just passed in review come under the variety characterized by blue to very dark, almost black plagioclase, which in the greater number of exposures is to a greater or less degree granulated around the margins of the crystals. They belong to the Marcy type as named by W. J. Miller. We have some evi- dence that in the Mount Marcy quadrangle, as in the Elizabethtown, inclusions of an older consolidated variety have been caught up in a later irruption. On the northern slopes of Baxter mountain such inclusions have been detected by H. L. Alling and furnish some parallels with the observations recorded in Bulletin 138, pages 37-39. On Baxter mountain, however, gneissoid anorthosite is included in one of more massive texture. Apparently an older and probably viscous, cooling mass was given a gneissoid character by frictional drag near the edge. After it had chilled a renewed out- break of still molten matter from the depths, pecs uae and included fragments of the older chill. The Whiteface type. On the extreme northeast corner of the quadrangle, where the anorthosites of the usual variety are in asso- ciation with the Grenville strata, the plagioclase takes on the white color characteristic of the Whiteface type. The exposures are of such limited extent as compared with the great area of the Marcy type, and the type has been so well recognized as a border phase by the writer * and by H. P. Cushing ” that no further discus- sion is called for at this point. From the anorthosites to the syenites there are some passage forms. We note at times in the anorthosite microperthitic develop- ments which are much more characteristic of the syenites. In the syenite rocks in the mountains north of the Cascade lakes we may sometimes see large blue, rectangular labradorites in ledges appar- ently of green syenites. An intermingling of the two rocks is a feature of Pitchoff mountain. The observer is almost at a loss to decide where one ends and the other begins. Beneath the iron bridge which crosses the East branch exactly a mile south of the northern edge of the quadrangle, ledges of syenite are again extensively exposed and contain blue labradorite crystals. Either an intermedi- ate magma has led to their development, or else the later syenite has absorbed older anorthosite almost but not quite to extinction. Inclusions in the anorthosites. On an earlier page in speaking of the Grenville gneiss, several inclusions in anorthosite were 1Kemp, J. F., N. Y. State Mus. Bul. 138, p. 35-37. 2 Cushing, H. P., N. Y. State Mus. Bul. 95, p. 310-12. 34 NEW YORK STATE MUSEUM described, which cast some light on the nature of the Greriville rocks. Others have, however, been noted which are anomalous. On the trail to the summit of the Gothics, inclusions were found by the writer as early as 1898 both at the summit and about 200 yards below it. In 1915 they were discovered still more abundantly by H. L. Alling. The one on the summit was about a foot in diameter and appeared to be a mass of gray gneiss, roughly rhomboidal in shape. Under the microscope about three-fifths of the slide is plagioclase, with the extinctions of labradorite and often micro- Tt ay yd EONS y A a! A sae & aN “is ee E33“ hi? BS = ~ or \ SE EAR CAEL S ERE NY NY NEON RELY are, = Oey, 2 j i ae | OA WIMNMOMOAMNATER a Fig. 5 Detail of dark, gneissic inclusions in anorthosite, Roaring brook, Giant trail perthitic. The two-fifths of dark silicates are chiefly hypersthene. -Brown hornblende is subordinate and red garnet occasional. Mag- netite is common. ‘The grain is fine, ranging from 0.1I-0.2 mm in diameter. The mineralogy reminds one of the dark rock which appears in the Avalanche lake dike and in at least one other exposure, GEOLOGY OF MOUNT MARCY 35 but the feldspar is more abundant and the explanation of small angu- lar fragments in a great anorthosite mass is difficult. The inclusion and others in the vicinity are undoubtedly fragments of Grenville sediments which have been saturated with anorthosite magma. A very peculiar exposure appears on Roaring brook, along the trail up Giant from the Keene valley. The area is very near the border of the Elizabethtown quadrangle and may be in the latter. It has been mapped on the Elizabethtown sheet as a small syenite area in the anorthosite. Anorthosite is the most extensively exposed country rock. In the valley of the brook it shows extraordinary brecciated contacts with the darker rock, which was earlier inter- preted as a basic syenite but which, despite mineralogical: parallels with the syenites, is now believed to be Grenville. The accompany- ing figure (figure 5), is a sketch to scale of the dark inclusions, and the succeeding figure (figure 6), is of a fragment of gneissoid rock, whose minutest crenulations were parallel with the contact. Fig. 6 Detail of an inclusion of Grenville gneiss in anorthosite, Roaring brook, Giant trail In Bulletin 138 (page 39) mention is made of a peculiar dark rock which appears near the woolen mill, about a mile west of the large hotels of Elizabethtown on the main road to the Keene valley. In the bed of the brook which furnished the mill with power were formerly exhibited excellent contacts against the anorthosite. The relations are illustrated in detail in figure 7 of Bulletin 138. A recent freshet has now buried them in sand. The rock was a dark, gneis- soid variety of moderate coarseness of grain. While showing some blue labradorite phenocrysts, it chiefly consisted of deep green 3 36 NEW YORK STATE MUSEUM pyroxene, plagioclase, orthoclase, quartz, garnet, magnetite, apatite and pyrrhotite. Two analyses were given showing marked contrasts of composition. . _An exposure of what appears to be the same peculiar rock is to be seen in the Mount Marcy quadrangle in the bed of Johns brook just below its junction with Ore Bed brook and Slide Mountain brook. A second series of exposures appears in the cascading portion of another brook which comes down to Johns brook from the north- west side of Wolf Jaws mountain. The writer’s early observations have again in this instance been corroborated and amplified by H. L. Alling. In the field one would be inclined to regard the rock as a member of the basic gabbro series, but upon examination with the micro- scope it is found to be very different both in mineralogy and texture. The rock consists of irregularly shaped crystals of variable sizes and in places apparently granulated from crushing. The chief feld- spar is orthoclase, at times microperthitic. Carlsbad twins may be detected. The microperthite is very fine, much more so than in the general run of Adirondack rocks. There is some plagioclase, but the extinction angles generally seem too small for labradorite, and indicate a more acidic variety. In at least one slide quartz is in notable amount. The dark silicate is emerald green augite, some- times in relatively small anhedra, that is, 0.I- 0.2 mm, sometimes in large ones, 0.5-3.0 mm. Strong pleochroism, green to pale yellow, may be obtained in favorable sections. The augite is in broken frag- ments of most irregular outline. There are a very few shreds of hornblende and biotite. The rock is richly provided with pink gar- nets, which in small and large anhedra are disseminated through and among the other minerals. They are at times in elongated shapes in plagioclase apparently developed from certain favorable lamellae. In amount the garnets rank well up with the feldspar and augite. In one slide titanite in unusually large irregular masses, 1.0—2.0 mm, is very prominent. Ilmenite altering to leucoxene, together with apatite, and rarely pyrrhotite concludes the list of components. Apparently this rock can be satisfactorily explained only as an old, surviving mass of Grenville gneiss, which became involved in the intrusive anorthosites and affected with more or less of the anorthosite substance. It shows the characters of both rocks. The result has been a dark rock, resembling to the eye the basic gabbros, containing at times large blue labradorite crystals, yet not agreeing with the basic gabbros when studied with the microscope. This GEOLOGY OF MOUNT MARCY 7 Go explanation would remove also certain difficulties met in other exposures, which have been referred not unnaturally from the vari- | able mineralogy sometimes to the syenites, and sometimes to the gabbros. In the exposures at the woolen mill locality in Elizabeth- town there was some evidence of anorthosite tonguing into the dark, supposed gabbro. This was a relation attributed to pressure effects, when the dark rock was classed with the basic gabbros which are later in age than the anorthosites. If, however, the dark rocks are surviving inclusions of Grenville sedimentary gneisses impregnated with matter from the anorthosites, the resemblance now to gabbros and now to syenites might be reasonably explained, as would also the apparent older age of the dark rocks. Exposures are as a rule lim- ited. They run a short distance along a brook bottom, and then disappear beneath the drift or forest growth. Besides the inclusions already mentioned there are often seen on the mountains adjacent to the Keene valley and in the northern halt of the quadrangle, large masses of brown, rusty gneiss caught up in the anorthosite. They vary from a foot or less across and 5 to 10 feet long, to other hundreds of feet in each diameter. Sometimes rather pure quartz-orthoclase rock, they at other times (and espe- cially the small ones) are rich in garnet and dark silicates. Much uncertainty has been felt in their study as to whether they were intrusive masses of syenites, as suggested by their weathering a rusty brown; or whether as is demonstrated by the small, angular individuals, they are inclusions of some older rock in the anorthosite. Difference of opinion might well arise in regard to the large masses, whose peripheral relations are obscure. But even in the case of some of these, the anorthosite appeared to cut in under them and to sup- port the view that they are old inclusions of Grenville gneiss. They appear on Baxter, Hopkins, Big Slide, Porter, Roosters Comb, Gothics, and doubtless other peaks. An instance at the summit of Giant mountain in the Elizabethtown sheet was interpreted in Bul- letin 138 as a syenite dike. Additional experience has led, however, to the interpretation here favored. In Bulletin 170, on the North Creek quadrangle, Prof. W. J. Miller has mapped an unusual number of large and small intrusive masses of basic gabbro and has applied to them very careful micro- scopic and statistical mineralogical study, whose tabulation is given on page 29. Expressed in percentages by volumes the values for orthoclase are to those for oligoclase-labradorite as 32:10, 32:20, 50:15, and 45:15, showing in four out of the fourteen cases tabu- 38 NEW YORK STATE MUSEUM lated a great excess of orthoclase and strong affinities with the syenites. There are no exposures of anorthosite in the North Creek area, but the gabbros have come up through granite-porphyry, granite, quartz-syenite, and Grenville gneisses. If now we imagine a quartz-orthoclase Grenville gneiss caught up in a lime-rich, anor- thosite magma and impregnated with the latter, a richly garnetiferous rock, with enlarged proportions of bisilicates might easily result. Even an aggregate not appreciably different from a garnetiferous member of the syenite series is possible. An origin of this sort for the basic syenitic masses which have been now several times encoun- tered and which have been extremely difficult to classify, is deserving of very serious consideration. The Garnet “reaction-rims” of the anorthosites. Since the time of Professor Leeds’s studies upon the anorthosites the presence in them of rims of garnet surrounding the pyroxene and titaniferous magnetite has been a matter of record and knowledge. In the sum- mer of 1914 the writer collected some exceptionally good material from a large boulder on the Chapel Pond road from the Keene valley to the valley of the Schroon river. Fortunately in the fall of 1914, Max Roesler, who had had some years of experience with the contact zones between intrusive rocks and limestones in Arizona, was studying with the writer at Columbia University, and under- took the investigation of the reaction-rims. Mr Roesler in the latter half of the university year became instructor in the Sheffield Scien- tific School at Yale University and completed his paper at the latter institution, where he had the valuable advice and suggestions of Professor Pirsson and the aid of Dr Walter F. Bradley in the chemi- cal analysis. The results are here introduced as a contribution on one feature of the anorthosites which is of much petrographic interest. Coming after the recent studies of Prof. W. J. Miller on similar developments in the gabbros of the North Creek quadrangle, Mr Roesler’s paper carries the subject a step further. For the con- tribution the writer takes pleasure in expressing his indebtedness. 4 } y ? % ;\ ae ee. GEOLOGY OF MOUNT MARCY 39 SOME GARNET REACTION-RIMS IN ANORTHOSITE BY MAX ROESLER The hand specimens show irregular masses, of rudely lenticular shape, of brownish green pyroxene with associated magnetite, or else single pyroxene crystals, surrounded by rims of dark-red garneis with associated quartz. These garnets are very small and no indi- vidual crystal has been found that has a diameter greater than one millimeter. The ground mass in which these lenses and rims lie is a typical granulated anorthosite such as is common in the Adirondacks and as has been described by F. D. Adams* from the areas in Quebec. That is, it is light colored, granular, with occasional indi- viduals of larger size that retain the blue-gray coloring of the fresh labradorite. This description applies to all the fragments except one, in which there is in the ground mass a very considerable amount of quartz in scattered crystals. For reasons which will appear later, and for the sake of distinguishing it from the ordinary anorthosite, this specimen will be spoken of as the aplitic anorthosite. Thin sections were made of the various parts of several of the specimens, and their examination gives the following results. The ground mass of the ordinary anorthosite is composed of plagioclase, granular, irregular in outline, twinned as a rule with the twinning lamellae often bent. In some of the grains of plagioclase there are inclusions of a clear material in a poikilitic arrangement and of lower index of refraction than the plagioclase. The inclu- sions are probably orthoclase. The plagioclase, judged by the extinc- tion angles, is very close to labradorite, more often varying toward the more acid than toward the more basic varieties. There are occasional grains of orthoclase in one of the sections. As a rule they are limited to the inclusions in the labradorite. Plate 16 A illustrates these inclusions of orthoclase in the labradorite. The section made of the ground mass of the “ aplitic ”’ anorthosite showed the following: Quartz in large grains, badly strained, but with very little evidence of granulation. Orthoclase in large grains, also badly strained, but not granulated. Mlicrocline, several grains. Neither the quartz nor the feldspar shows good crystal outlines. Labradorite in a few small scattered and broken grains. These plagioclase grains show at times a graphic intergrowth with quartz. In one case the quartz within the plagioclase showed the same orientation as the quartz in interstices between the plagioclase grain 1 Geol. Survey of Canada, Annual Rep’t, v. 8, pt. J, p. 107-10. 40 NEW YORK STATE MUSEUM and the surrounding grains. Occasional small grains of a micro- eraphic intergrowth of quartz and orthoclase. Some of the ortho- clase shows a microperthitic structure. In this connection there was studied, thanks to Professor Pirsson, a thin section of the contact of an aplite dike in an anorthosite from Grand Discharge, Saguenay, Quebec. This aplite differs from the above only in that the quartz is less abundant and in smaller grains relative to the orthoclase and microcline. Also, there is no micro- perthite, and the orthoclase shows a tendency toward idiomorphism. The garnet rims themselves show no variation in any of the thin sections of these specimens. They are entirely composed of pink garnet, rarely showing good crystal faces, and no anomalies. They are intergrown with and include grains of clear unstrained quartz. The quartz and garnet together form almost complete envelops about ferromagnesian cores. Their relations are illustrated in plate 16B. A more comprehensive illustration showing both the labra- dorite on the one side and the pyroxene on the other is given in plate LIM The thin sections of the core within the rims show that it is com- posed almost entirely of pyroxenes. These pyroxenes are pale green in transmitted light and show pleochroism either from pale green to pink or pale green to a very slightly darker green. Further exam- ination shows that the pyroxene with the pleochroism to pink is orthorhombic and answers to the description of hypersthene. The other pyroxene is monoclinic and appears to be a variant of augite. As the extinction angle is uniformly high it would seem that the pleochroism is due to the presence of a ferrous iron (hedenbergite) molecule, rather than of a soda (aegirite) molecule. Both pyroxenes show in places good crystal faces. As accessory minerals in these pyroxenic cores, there are magnetite, a small amount of alteration products: epidote, calcite, uralite, and more or less interstitial, clear quartz. Plate 17B is a photograph of part of a section cut from what appeared in the hand specimen to be a single crystal. It shows an intergrowth of the hypersthene and the augite. The light-colored areas over the entire photograph are augite, the dark-colored areas hypersthene, and the black grains magnetite. It is of interest to compare these relations with the descriptions of similar ones given by F. Zirkel in his paper on “ Urausscheid- ungen in rheinischen Basalten,”’ (Segregations in basalts of the Rhine), page 34. He says: “ Extraordinarily clear are the inter- Plate 16 A. Microperthitic intergrowths of orthociase (O) in plagioclase (Fs). Quartz is labeled (Q,. Crossed nicols, : actual field 0.08 inch or 2.0 mm. B. Garnet and quartz in the reaction rims. Q is quartz; G is garnet. White light, actua! field 0.05 inch or 1.3 mm. Plate 17 _A. Garnet reaction rim showing the labradorite (Fs) with included orthoclase (Or), on the left; garnet (G) in the center, succeeded by quartz (Q) and pyroxene (Px) on the right. White light, actual field 0.08 inch or 2.0 mm. B. Section of intergrowths of pyroxene, var. heden- bergite (Px), and hypersthene (Hy). Magnetite 1s (Mg). Crossed nicols, actual field 0.08 inch or 2.0 mm. GEOLOGY OF MOUNT MARCY AI growths, repeatedly observed, of fine lamellae of monoclinic augite in these enstatites.’’ Plate 18A is a photograph of an area of pyrox- ene, in the ground mass of anorthosite, which is not surrounded by garnets, but which shows a good development of a green amphibole thought to be uralite. From one of the specimens with a favorable reaction rim, enough of the garnet was sorted out for the making of duplicate chemical analyses which give the following as an average: SiO, 40.11 Al:Os 22.90 Fe.O; .60 FeO 25.31 MgO 4.46 CaO 6.19 MnO trace TiO. none 99.57 An attempt to recast this analysis indicates that the elimination of quartz and feldspar was not complete. It shows, however, the presence in the garnet of the almandite, pyrope and grossularite mole- cules. Their ratio to one another is probably about 3 parts almandite, 3FeO, Al,O,, 3SiO, I part pyrope — 3MgO, Al,O,, 3510, I part grossularite 3CaO, Al O,, 3SiO, The amount of grossularite is open to question since some of the calcium may have come from labradorite. A summary of the facts shown by megascopic, microscopic and chemical examination follows: There are in this rock aggregates of pyroxene made up mostly of a variety of augite and partly of hypersthene with accessory magne- tite and interstitial quartz. This quartz shows no strain shadows. These aggregates may or may not be surrounded by garnet rims. Where the garnet rims are lacking, there is a greater development of uralite than when they are present. The garnet rims are composed of garnets containing the almandite, pyrope and grossularite molecules, and of unstrained quartz grains. The ground mass is as a rule a normal granulated anorthosite. In one case it is an aplite showing strain and containing grains of broken labradorite. Unfortunately, the hand specimen is not sufficiently large to show the relationship between the aplite and anorthosite, and this relationship must be left to inference on a very meager basis of fact. 42 NEW YORK STATE MUSEUM In connection with this work a number of thin sections of other garnet occurrences in the Adirondacks were studied and, in part, photographed. These sections have been supplied by Professor Kemp and have been in part previously described by him. Plate 18B illustrates a reaction rim in the basic gabbros. It intro- duces biotite. Plate 19 contains two cases of garnet growths from the contact zones produced from limestones by the intrusives. The upper illustration (A) is taken from a slide from the same exposure as is illustrated in plate 8. Narrow zones of garnet have developed between the pyroxene (hedenbergite) and scapolite. The lower illustration (B) brings out a very peculiar interfingering or parallel growth of pyroxene and garnet, from the Weston mine. Nothing in the nature of a rim is presented by the slide, but rather the intimate relations which the production of pyroxene in a limestone contact bears to that of garnet. Similar intergrowths of garnet in the multi- ple-twinned plagioclase, the garnet taking the place of alternate lamellae have been described by Professor Kemp.* Plate 10B illus- trates the formation and relations of garnet in a gneiss of the gen- eral composition of the syenites and believed to belong to them. While the feldspar is predominantly orthoclase, acidic plagioclase also enters, and probably contributed to the garnet. Discussion. Upon the basis of the evidence presented and upon the observations of others a satisfactory explanation of the reaction rims must be based. Search through the literature revealed the fol- lowing. The earliest reference to a case at all similar is given by A. Lacroix in a paper on “Gneiss a Pyroxene et a wernérite de Bretagne,” printed in the Bulletin de la Société Minéralogique de France, v. 12, 1889, p. 85-365. In giving a description of some rims around olivine he refers to an article by Tornebohm on some rims about olivine in the gabbros of Wermland.” The original paper of Tornebohm’s was not available but, accord- ing to the citation in Lacroix, it dealt with rims of other minerals than garnet. Lacroix himself describes, among others, some rims of garnet, between labradorite and amphibole which surround pyroxene around biotite around a core of magnetite. These rims occur in a gabbro at Odegarden, which is in contact with an amphibole gneiss. The only comment made in regard to origin of the rims is “ Dans le roches que nous étudions, il semble difficile d’admettre que le grenat soit exclusivement formé au contact du gneiss amphibolique.” 1 Kemp, J. F., “ Gabbros oe Le Western Shore of Lake Champlain.” Bul. Geol. Soc. Am. 1895, 5 :219- 2 Kongl. Svenska Vetensk. Rea Fordhandl, i. Stockholm, 1877. SS a ’ e Bae ae es A. Pyroxene (Px) and hypersthene (Hy) in con- tact with labradorite (Fs) and with no reaction-rim of garnet, but with associated uralitic hornblende (Hb). Crossed nicols, actual field 0.08 inch or 2.0 mm. B. Narrow reaction-rim of garnet (G) between lab- radorite (Fs), clouded by innumerable minute inclu- sions, and an inner core of biotite (Bi), hornblende (Hb), magnetite (black) and quartz (Q). White light, actual field 0.08 inch or 2.0 mm. Plate 19 A. Narrow zones of garnet (G) between pyroxene, var. hedenbergite (Px), and scapolite (Sc). From the same locality as plate 8. White light, aciual field 0.08 or 2.0 mm. is. Intergrowth of garnet, the dark mineral (G) with pyroxene, var. hedenbergite (Px), the light mineral. Contact zone, Weston mine. Crossed nicols. Actual field 0.08 inch or 2.0 mm. GEOLOGY OF MOUNT MARCY 43 (Opus cit., p. 236) “In the rocks which we are studying, it seems ' difficult to admit that the garnet should be only formed along the contact with the hornblende gneiss.” The first mention of garnet rims in the Adirondacks that has come to the writer’s notice is in the paper by A. R. Leeds, ‘“‘ Notes upon the Lithology of the Adirondacks.* ” In describing a specimen he says, “‘ Garnet is not unfrequently dis- posed as a red border around the greenish masses of diallage, along the bounding surfaces between it and the labradorite.” No theory of their formation is mentioned. . Since Professor Leeds’s paper, garnet rims from the Adirondacks have been described by J. F. Kemp* and W: J. Miller® in various articles. This list does not claim to be a complete one, but gives those artti- cles which have been of particular interest to the writer. J. F. Kemp, in the article on the titaniferous iron ores, speaks of an occurrence in gabbro which “has been somewhat squeezed, so that secondary garnets have been developed in quantity.” W. J. Miller (op. cit., p. 30 and 31) describes several rims, some of garnet, others lacking the garnet and composed entirely of other ferromagnesian minerals. He designates them as “reaction or corrosion rims’”’ and also says that “ Garnet is almost invariably in contact with feldspar which suggests the partial formation, at least, of the garnet from feldspar.” Another occurrence of garnet that must be mentioned in this con- nection is that described by F. Zirkel.* In this case the garnet occurs not as rims but as aggregates in a basalt, and has been regarded a as primary. The study of the specimens and the literature suggested four possi- ble modes of formation for the garnet rims: (1) that these lenses represented stoped-in fragments of the rock invaded by the anortho- site and metamorphosed to pyroxene-garnet masses; (2) that the garnets were primary and the zonal arrangement due to the order of crystallization; (3) that in this particular case there had been an addition of silica due to an aplitic invasion; (4) that the garnets 1 Thirtieth Ann. Rep’t, N. Y. State Mus., 1876. 2J. F. Kemp, “Gabbros on the Western Shore of Lake Champlain,’ Bul. Geol. Soc. America, v. 5, p. 217-21, 1894. J. F. Kemp, “The Titaniferous Iron Ores of the Adirondacks,” pt 3, 1oth Ann. Rep’t, U. S. Geol. Surv., 1897-08. 3W. J. Miller, “Geology of the North Creek Quadrangle, Warren County, New York.” N. Y. State Mus. Bul. 170, 1914. 4“Uber Urausscheidungen in Rheinischen Basalten,” Leipzig, 1903. 4A NEW YORK STATE MUSEUM were the result of reaction between the ferromagnesian core and the feldspathic ground mass. The first theory made a peculiarly strong appeal to the writer since, to one familiar with the geology of copper mines, garnet connotes contact metamorphism. In favor of this theory is the fact that the Adirondack anorthosites do cut such sediments as might give inclusions that would alter to garnet rocks. Also the boundary between the garnet surrounded masses of pyroxene and the ground mass is at times very sharp. But the evidence against this theory is too strong. The pyroxenes in those aggregates surrounded by gar- net differ in no way from pyroxenes in the rest of the rock and are apparently endogenous. The garnets are not limited absolutely to the rims about the pyroxene; an occasional individual is found out in the feldspar, and also within the pyroxene mass. Furthermore, if these rims and lenses had been formed by contact metamorphic action on stoped-in fragments, they must have been produced previous to the later dynamic metamorphism which granulated the mass of the rock. In the hand specimen they show no effect of such metamorphism, the lenticular masses lying in the rock without any tendency toward parallelism. The slides show no granulation of the pyroxenes. There is then the possibility that the fragments represent a stoped-in pyroxenite about which the garnets have formed later. This seems rather unnecessary when the same pyroxenes are found undoubtedly endogenous in the normal rock. The next theory is that these entire lenses, both garnet and pyrox- ene, represent primary segregations like those described by F. Zirkel in basalts (op. cit.). This does not require that we ascribe to a gabbroic magma, contact effects that are usually associated with more acid intrusives. It is, moreover, an explanation which accounts for the pyroxenic aggregates and the garnet at the same time. The same objection as to lack of granulation in these masses formed prior to the dynamic metamorphism holds against this theory as applied to the garnet rims. But if it can be shown that the garnet rims are the expression of that dynamic metamorphism around the pyroxenes, there is no reason why the pyroxenes may not represent such segregations. Another objection to regarding the entire lense, rim and all, as an original segregation, is the comparatively large amount. of quartz present. This quartz is entirely lacking in strain shadows and has all the appearance of being contemporaneous with the garnet. = ee eee GEOLOGY OF MOUNT MARCY AS The theory that the garnet formation is due to silica from an aplitic invasion hinges upon one specimen. It is rather difficult to offer evidence either for or against this case. The aplite is very badly strained and so shows that it has been subject to some dynamic metamorphism. It includes some small grains of basic plagioclase, but whether these are part of the already granulated anorthosite or have been included prior to granulation is not definitely shown. The writer is of the opinion that the aplite invaded the rock after most of the granulation had taken place, but this opinion is based on very slight evidence and is not a conviction. Since the aplite has been observed in only one specimen it can certainly not be regarded as playing any important role in the majority of cases and may be disregarded. There remains the explanation that the garnet rims are due to reaction between feldspars and ferromagnesian minerals. This process has been suggested by J. F. Kemp and accepted by later observers, but so far as the writer knows there has been no very complete discussion of it. Applied to the specimens in hand, it seems to meet all the facts. The garnets lie between a basic plagioclase ground mass and an aggregate of augite and hypersthene. They are composed of the lime, the magnesia, and the ferrous-iron-bearing garnet molecules as shown by analysis. The hypersthene could supply some of the magnesia, ferrous iron and silica. The augite could supply more of the ferrous iron and magnesia, some of the lime and some of the alumina and silica. The ferric iron of the augite could have gone into the formation of some of the magnetite. From the basic plagioclase the anorthite molecules could add more lime, alumina and silica. The slides show an excessive development of silica, contemporaneous with the garnet and some of the magne- tite. This also accords with the conditions. To take the simplest case ; hypersthene (Mg,Fe) SiO, reacting with anorthite Ca Al,Si,Os, to form a garnet Ca Mg Fe Al,(SiO,),. This would require two hypersthene molecules and one anorthite and could be written: Ve@FeO (S105); CaO-.Al,O;(Si0;), =) CaO: MgO: FeO:ALO, (SiO,),-+-SiO,. The presence of quartz may then be regarded as a partial confirmation of the reaction. The greatest difficulty is to account for the albite molecule which must have been associated with the anorthite in the plagioclase. In the thin sections certain small grains and inclusions were determined as doubtful orthoclase or microline. It is quite possible that these are anorthoclase, and 46 NEW YORK STATE MUSEUM might account for some of the soda. If this is admitted, and the lack of a definite accounting for the soda not regarded as an insuper- able obstacle, the possibility that the garnets represent a reaction between feldspar and the pyroxenes has been established. ‘The cause for the reaction seems to lie in the dynamic metamor- phism. F. D. Adams, in the work cited above, mentions the fact that the pyroxenes in the granulated anorthosites of the Morin area were also granulated. The pyroxene in the specimens under dis- cussion show no such granulation. It seems to the writer that this indicates that the specimens come from an anorthosite that was granulated under conditions differing from those that obtained in the Morin area. Possibly a greater development of heat permitted a fusion and recrystallization around the edges of the pyroxenic aggre- gates. There may have been a greater amount of water or of other mineralizers which permitted fusion at a lower temperature in these pyroxenes. In fact, tests for combined water show 0.56 per cent in the pyroxene and 0.34 per cent in the granulated anorthosite away from the rim. Whatever the cause may be, any explanation which does not admit that these garnet rims are the expression of the dynamic metamorphism that caused granulation in the rest of the rock, must either show the entire lenses to have been introduced later than the metamorphism, or else give some other accounting for the lack of granulation. If, however, these rims are admitted to be the expression of the dynamic metamorphism, there is no further cbjection to regarding the pyroxenic aggregates as original segrega- tions. There remains the fact that certain small areas of pyroxene in the specimens are not surrounded by garnet. These areas are made up of very small crystals and show a great development of amphibole which appears to be secondary. Plate 18A shows this. In this case the amphibole formation represents the metamorphism. After regarding the various views suggested, the one that seems most tenable is that the garnet rims represent a reaction between pyroxene and feldspar induced by the same causes that brought about the granulation of the ground mass. This conception has the advantage of being widely applicable, as its requirements are very few: a ferromagnesian mineral in contact with a feldspar, and the proper degree of heat and pressure. It certainly seems to the writer to fit almost all the cases that he has studied or whose description he has read. . . q : | GEOLOGY OF MOUNT MARCY 47 COMMENTS BY J. F. KEMP It will be noted that in one of the specimens studied by Mr Roesler, . minerals suggesting an aplitic addition to the anorthosite from an outside source were observed. Some apparent corroboration of the suggestion was gained from a specimen of Canadian anorthosite with an aplite dike, in the collection of Professor Pirsson. Yet all the specimens furnished Mr Roesler by the writer came from one large ‘boulder of otherwise normal anorthosite, and no intrusive dike of any sort appeared in it nor have we yet observed aplite intrusive in the anorthosites.1 Pegmatites of granitic composition are known in a few cases, but nothing as yet that would be described as aplite. The aplitic minerals would appear to be necessarily due to some reaction in the anorthosite itself. With regard to the formation of the reaction rims it may be further noted that they appear around large and thoroughly uncrushed crystals of labradorite, caught in the great masses of titaniferous magnetite on Lake Sanford, in the ‘neighboring Santanoni quadrangle; and that they are observable sometimes in the basic gabbros which are still not appreciably granu- lated. They may in instances, at least, be due to some magmatic corrosion of older formed minerals, and in the closing stages of crystallization. Nevertheless the garnets in the thoroughly mashed anorthosite would seem to be the results of some reaction of pyrox- ene and labradorite, incident to the dynamic metamorphism because they are sometimes from half an inch to an inch in diameter, not apparently granulated, and looking in the crushed anorthosite much like a red knot in a pine board. Peculiar gabbro. In one of the earlier season’s work a ledge was — observed which had been blasted shortly before in highway improve- ment and which proved to be a very curious departure from the normal anorthosite. The locality is on the old road from Keene valley to the Ausable Club (Beede on the map), and within one- fourth of a mile of the forks. In recent years a new road has been built farther west. The rock impresses one as a gabbro-porphyry. Large, rectangular pale-green crystals of labradorite are set in a blackish green finer grained matrix. Under the microscope. the dark-green ground mass is resolved into granular, green augite. Some augites are larger than others, but as a whole granulation is 1 Since the above was written H. L. Alling has found a narrow aplite dike several inches in width cutting an anorthosite boulder on East hill, northeast corner of the quadrangle. Under the microscope the essential minerals are quartz, soda-microcline and microcline-microperthite. The accessory minerals are magnetite, uralite, biotite and diopside. There is considerable garnet in the rock which is regarded as resulting from metamorphic action. 48 NEW YORK STATE MUSEUM pronounced. There are rather coarse masses of titaniferous magne- tite, altering to leucoxene. This peculiar type of rock was noted in the Elizabethtown quadrangle near New pond (Museum Bulletin 138, p. 43) and has also been observed just north of the edge of the Mount Marcy quadrangle, on the east bank of the Ausable river above Keene Center. The rock under pressure and shearing would readily change into horneblende gneiss with parallel bands of feldspar and horneblende. It is undoubtedly the parent rock of some puzzling gneisses. Exposures have proved so limited that observations are insufficient to prove whether it is a separate intrusive mass or a peculiar phase of pyroxenic anorthosite. Its affinities are with the anorthosites. A a By ee ae? GEOLOGY OF MOUNT MARCY AQ | 4 THE PRECAMBRIAN INTRUSIVES, CONCLUDED The Syenites. The syenites are developed in the northern edge of the sheet. They present the usual dark green gneissoid rock, now become widely familiar in the Adirondack area. Under the micro- scope microperthite is the chief component. The spindles of albite which give the feldspar the microperthitic character are sometimes “set in orthoclase, sometimes in microcline. Plagioclase appears in a - subordinate capacity in the typical cases, but in the syenite of Pitchoff mountain on the borders with the anorthosite, it sometimes becomes quite prominent. The syenite has acquired or developed blue labradorite crystals and one does not know with which series of rocks, syenites or anorthosites, to place the specimens. The most typical dark silicate is emerald green augite, presumably of a soda- bearing variety. Brown or green hornblende is also present, and at times hypersthene. Stray bits of magnetite and the small accessories, zircon and apatite, make up the balance. The characteristic syenite has been collected on a shoulder of Scott’s Cobble. It is illustrated in plate 20A. Elsewhere in this hill it shades into siliceous varieties with much quartz, practically a granite. These variable characters have, however, not infrequently been observed in the extended exposures of syenite elsewhere. No analyses have been prepared of the syenites within the Mount Marcy quadrangle but a number are given of specimens in Bulletin 138, page 45, and the rocks are treated at length by Professor Cush- ing in Bulletin 115. Pegmatite. On the western shoulder of the summit of Mount Porter, C. H. Fulton, the writer’s assistant in 1897, noted in the anorthosites a pegmatite vein mainly containing microcline and quartz. In the summer of 1914 the writer and H. L. Alling were on the eastern shoulder of Mount Porter and were impressed with a small series of pegmatites containing microcline as the feldspar. They filled crevices in the anorthosite. The association is a peculiar one in a rock so low in potash as the anorthosite. We know of no other intrusive rock near, which might have supplied the pegmatite. A parallel is mentioned in Bulletin 138 where orthoclase pegmatites in association with the basic gabbro are mentioned from the Elizabeth- town-Port Henry quadrangle. Prof. W. J. Miller describes the same peculiar association in the North Creek quadrangle in Bulletin 170, page 38. A pegmatite dike also appears east of the included lime- stone at the Cascade lakes. 50 NEW YORK STATE MUSEUM Granite. While rocks of granitic composition have been observed they seem to be so closely connected with the syenite series as to be mapped with them. On Scott’s Cobble along the northwestern edge of the sheet this is true. There are, however, in the bed of the East branch in the Grenville area on the northern border, some very nar- row dikes of pink granitic rock which traverse the old Grenville sediments and merely deserve passing mention. There is also a very small exposure of red granite on the east pass of Baxter mountain, where the two branching trap dikes are mapped. The granites do not constitute a sufficiently large member in the local geology to receive a special color on the map. Gabbro-syenite of the basic gabbro series. In the summers of 1888, 1889 and 1890 the writer was in the field accompanied by V. F. Marsters studying the trap dikes of the Champlain valley and neigh- boring mountains.» Having read in Prof. Ebenezer Emmons’s Report on the Second District, page 215, of the great trap dike at Avalanche lake,” we made a trip into the mountains to visit it. As the dike lies in a steep-walled gorge between the main mass of Mount Colden on the south and its northern shoulder, sometimes called Avalanche mountain, it impressed the writer as a mass of sheared and dynamically metamorphosed rock in a faulted zone. It was there- fore described as “ The great shear zone near Avalanche lake in the Adirondacks,” in the American Journal of Science, August 1892, pages 109-14. The contrasted mineralogy of the dike when com- pared with the anorthosite walls was thought to be due to crushing and recrystallization. The decided abundance of garnet, which was considered a metamorphic mineral, and the finely crystalline, granu- lar nature of the rock gave some color to the view. Mineralogically the dike consisted of predominant, irregular and rather fine-grained hypersthene, augite, garnet, hornblende and magnetite, with less abundant plagioclase and orthoclase, all showing crushing. The neighboring walls are coarsely crystalline anorthosite. At this time the writer was familiar with the diabase dikes of the mountains and with the trachytic and rare basaltic rock types in the dikes of the 1The results found publication as Bulletin 107, of the U. S. Geological Survey, 1893. 2Even earlier mention of the dike is made by W. C. Redfield in “Some Account of Two Visits to the Mountains of Essex Co., N. Y., 1836-37,” Amer. Jour. of Science, Ist series, 33:301. On one of these expeditions, both of which were undertaken to examine the iron ores of Lake Sanford, James Hall accompanied Mr Redfield. Professor Emmons was with him on the other. Interest in the iron ores was very keen at the time. Professor Emmons describes the dike also in the Second Annual Report, N. Y. State Survey, 1838, p. 225, Atlas, pl. 4. Plate 20 A. Syenite from Scotts Cobble, comtaining microper- thite (M), brown hornblende (Hb), and quartz (Q). Crossed nicols, actual field 0.08 inch or 2.0 mm. B. Plumose border of bostonite dike on the left, against Grenville gneiss on the right. Crossed nicols, actual field 0.08 inch or 2.0 mm. ac ‘ *. . r a > _ =. GEOLOGY OF MOUNT MARCY 51 Champlain valley, but the basic gabbros of the mountains had not yet been recognized. To this latter group the dike undoubtedly belongs. Prof. Ebenezer Emmons was entirely correct in regarding it as © igneous and in calling it a trap dike. It does, however, exhibit effects of crushing and perhaps some recrystallization but it is too basic and too rich in iron and magnesium to have been derived from anorthosite. Undoubtedly it entered as a large basic dike. When subsequently exposed at the surface its relatively easy weathering produced the gorge. The dike strikes N. 50-60° W. Near the lake it is 75 feet wide. Its dip is vertical. Professor. Emmons states _ that the dike can be traced up Mount MacIntyre across the lake. The dike is peculiar in the amount of orthoclase which it contains. There is enough to make one hesitate whether to class it with the basic syenites or basic gabbros. This difficulty has been avoided by calling it gabbro-syenite. No statistical measurements have been made, but the rock is obviously much like the gabbros rich in ortho- clase such as are described by Prof. W. J. Miller in the North Creek area (Bulletin 170, page 29) and as mentioned on a previous page of the present contribution. In 1895 in going from Avalanche Lodge to Lake Sanford by way of the Indian pass the writer noted another dike of this same character, nearly 3 miles to the northwest of Avalanche dike and with a parallel strike and dip. As nearly as could be determined the new exposure is just where the trail southwest from Clear lake leaves the Mount Marcy quadrangle. If the location is correct, the dike last discovered is somewhat north of the line of the strike of the Avalanche dike; but its course is in the same direction. Apparently two intrusive masses entered the anorthosite along similar general lines of weakness. Basaltic dikes. The last member of the hard rock formations con- sists of the series of basaltic dikes which are so widespread in the eastern Adirondacks. From fifteen to twenty have been discovered in the Mount Marcy quadrangle, but there are undoubtedly others. Almost without exception the observed dikes strike northeast and southwest parallel with one set of the large structural lines of the mountains. In most cases the dikes have found their way upward along these lines of weakness. They are of later introduction than the metamorphism of the ancient crystallines and may have entered long after the Precambrian so far as any local evidence to the con- trary is available. The acute observations of Professor Cushing* in 1H. P. Cushing, “On the Existence of Precambrian and Postordovician rae Dikes in the Adirondacks.” Trans. N. Y. Acad. of Sci., 15 :248-52, 1800. 5 52 NEW YORK STATE MUSEUM Clinton county brought out as early as 1896 the existence of two series of basic intrusions, whereas before this time no such con- trasted grouping had prevailed. His field work along the edge of the Potsdam sandstone which rested on the older gneiss revealed many dikes of diabasic character in the gneiss, but none passing upward into the Potsdam. On the other hand we knew of trachytic (or bostonite) dikes and rare basaltic types (camptonite and others) which cut both ancient crystallines and Paleozoic strata up through the Utica slate. The basaltic dikes in the Mount Marcy quadrangle are dense, finely crystalline rocks whose exact mineralogy and textures can be - determined only with the microscope. Slides have not been prepared of every dike met and one can only say that to the unaided eye they seem in the cases from which no slides have been studied to be identical with the Precambrian diabases. On the other hand micro- scopic examination of a dike in the Johns Brook valley, just below ~ the entrance of Ore Bed brook, shows it to be related to the campton- ites. It consists of an interlacing mass of minute augite prisms about 0.05 mm broad by 0.5 mm long with many bits of magnetite in a matrix apparently plagioclase. The twinning of the plagioclase is often apparent, but is not always pronounced. There may be some other minerals, such as analcite, involved. The texture is exces- sively fine and with high powers the identity of the minerals is difficult to establish. Of much the same general character is the basaltic dike, 5 feet wide, shown in figure 1 and illustrated in plate 21. The phenocrysts are well bounded and usually zonal augites, brown, basaltic hornblendes and olivine. The ground mass is chiefly an interlaced aggregate of minute prisms of augite and hornblende, with some lighter colored minerals, presumably plagioclase and an- alcite or some similar alkaline-alumina silicate. With such small components it is difficult to get satisfactory tests in a naturally opaque rock. Magnetite in small irregular bits does not fail. Clearly these dikes, so far as microscopically studied, are camp- tonites and are related to the post-Ordovician dikes of the Cham- plain valley. This is a peculiar feature and may stamp them as a local outbreak of the same magma far in the mountains. The dis- covery of a fragment of a bostonite dike, although not in place, yet penetrating the rock regarded as Grenville gneiss partly digested in anorthosite, and near the headwaters of Johns brook, is another peculiar and corroborative observation. The camptonites and bos- tonites are associated in the Champlain valley. There is every reason Plate 21 A. Camptonite dike from the bed of the Ausable river, north edge of area. Augite (A). The ground- mass is a fine aggregate of brown. hornblende prisms and plagioclase, probably with analcite. White light, actual field 0.08 inch or 2.0 mm. B. The same rock as A, but showing brown, basaltic hornblende (Hb), olivine (Ol) and augite (A). White light, actual field 0.08 inch or 2.0 mm. GEOLOGY OF MOUNT MARCY 53 to think that the bostonite dike at the head of Johns brook came from some ledge in the immediate neighborhood. . . Prof. Albert B. Leeds, in connection with the analyses of anor- thosite and its constituent minerals earlier referred to, also made an analysis of one of the basaltic dikes, named by him dolerite, and stated to be intrusive in the’Norian rocks (that is, anorthosites, as we now use the term). Doctor Leeds also examined a thin section and has given us the following microscopic description (pages 28- 29 of the separate). From it we can do little more than conclude that the specimen came from a very dense, and presumably narrow dike, and that it probably was a camptonite: 21 Section of the dolerite, whose analysis has been previously given. A large portion of the transparent base of this rock could not be definitely referred by its optical characters to plagioclase. It presents a considerable admixture of quartz. The dark color of the section and rock is due in part to the magnetite and menaccanite, but in still greater degree to very minute light to dark green and yellowish-red masses. The former are probably pyroxene, the latter, which are by far the most abundant, hornblende. Doctor Leeds unfortunately does not give the locality whence the specimen was obtained. The rock with its high CO, and H,O was obviously not perfectly fresh, although some of the water may have been in analcite. All the water was in a soluble mineral, but it seems strange that some of the silica did not also go into solution. In so basic a rock, the quartz, if correctly determined, must have been secondary. In citing the analysis and its two associates the oxides have been rearranged somewhat, to conform with modern customs. Total Soluble Insoluble SiO, AB AT ips 43.41 m1O)> 0.35 0.367 Al.Os 19.42 9.097 10. 324 FeO; 5 72 4.553 1.169 FeO 6.69 6.693 MgO 5.08 5.285 0.605 CaO 0.11 7.308 1.711 Na.O 4.39 0.530 3.864 K:O 0.47 0.323 0.144 CO: 2.00 2.003 H.0 3.00 2.907 100.54 39.246 61.317 Sp. gr. 2.80 If we attempt to recast the analysis we can not assign all the Na,O to albite because then we will run short of SiO, for the anorthite, which must be in so basic a rock in even greater quantity than the albite. On the other hand, if we assume that the Na,O is in analcite or nephelite in sufficient proportion to ease the difficulty just stated, 54 NEW YORK STATE MUSEUM . we can not understand why these very soluble minerals did not go more largely into solution. Only by assuming some rather basic plagioclase and then assigning arbitrarily the soda to nephelite or analcite can a recasting be carried out and then the results in soluble and insoluble must be ignored. Recasting has therefore not been attempted. Bostonite. In the locality in the Johns Brook valley below the junction with Ore Bed brook a loose piece or boulder was discovered which was partly the dark rock regarded as an included mass of Grenville gneiss, and partly a trachytic or bostonite dike. The dike is of dense, felsitic texture, of pale green color, and about 35 mm, or 1.4 inches, wide. A thin section of the two at their contact revealed a remarkable plumose arrangement of the orthoclase rods, as illustrated in plate 20B. The border is 0.5 mm wide and is succeeded by the normal bostonite which is an interlacing mass of rods of orthoclase or perhaps anorthoclase. No dark silicates can be detected. The rods have an extinction closely if not invariably parallel with the elongation. The boulder is believed to have been derived from the ledges in the immediate vicinity. The bostonite dike is the first one met in the mountains south of the northern border. Dikes of this character are most frequently observed cut- ting the Paleozoic strata of the Champlain valley. Under the name of syenite-porphyry, however, dikes which cut the old crystalline rocks in Clinton county have been described both by A. S. Eakle* and H. P. Cushing.’ 5) FAULTS, AREAL DISTRIBUTION OF FORMATIONS Faults. In an area of predominant massive rocks such as the Mount Marcy quadrangle structure can not be worked out to any such degree as is possible in sedimentary and contrasted strata. Faults are the large structural features and yet they must often be a matter of inference from the precipitous topography. Sometimes, however, the crushed and decomposed rock can be seen. In the summer of 1910 a borrow pit for improving the highway on the west bank of the East branch of the Ausable river and just north of the edge of the quadrangle, revealed a zone of thoroughly crushed and kaolinized anorthosite, striking nearly parallel with the trend 1 Eakle, A. S., Amer. Geol., July 1893, p. 34. 2 Cushing, H. P, Bul. Geol. Soc. Am., 9 :230-56, 1808. a ne eee GEOLOGY OF MOUNT MARCY 55 of the Keene valley and evidently indicating a powerful fault. The crushed rock was still visible in 1914, although the exposure was not so fresh and clear. The fault seems to bear into the hill somewhat to the west of the valley as one goes north. To the south of this exposed and visible fault the East branch of the Ausable is in a deep, rocky postglacial gorge as described and illustrated by H. L. Alling in subsequent pages. The river has a - zigzag course because it uses sometimes east and west faulted and crushed zones, sometimes others north and south. The crushed zones can be detected at times in the hard gneisses, and one east and west one is occupied by a trap dike, 5 feet in width, which on the place exposed runs true with the stream. The stream turns to the north and follows the direction of a north and south crush which can be seen in the highway on the east bank where a strong fault breccia of gneiss is exposed. The locality is just in the edge of the sheet next the Lake Placid quadrangle on the north. The fault breccia consists of fragments of green, syenitic gneiss cemented by comminuted fragments stained by chlorite. The north and south lines of brecciation and crushing, we are justified in prolonging to the south in the depressions, less well exposed. On the east side of the Keene valley along the highway whose exterision formerly ran on the south side of Baxter mountain, and about a mile from the East branch of the Ausable river, is Beede’s rotten stone quarry. On the north side of the road, sheeted, crushed and decomposed anorthosite is quarried and used for macadam with excellent results. The decomposed belt, as exposed, is nearly 100 feet broad and has knots of less altered rock in it. The strike of the sheeting is almost due east and west, referred to the true north, and dips 45° to 55° north. It would supply a line of weakness for the development of an east and west valley, such as the one on whose side it appears. From the positive and well-exposed lines of east and west and north and south crushing, we are justified in inferring a series of faults with these strikes. We note, also, that their direction corre- sponds to some pronounced features of the relief, such as the Keene valley and the valley of Elk lake. Study of the map will also bring out the fact that the crushed and decomposed exposure at Beede’s rotten stone quarry is at the junction of the east and west fault-lines with one which comes to it in a southwest direction from the pass immediately southeast of Baxter mountain proper and which is prolonged farther to the south- BO NEW YORK STATE MUSEUM west in the Johns Brook valley. The Johns Brook valley heads on the east side of the summit of Mount Marcy and when the line of the depression is followed to the southwest across the divide, it passes straightaway down the steep-sided depression of Skylight brook. The line is almost mathematically parallel with the great fault-valley of the Ausable lakes on the southeast and the fault- valley of the Cascade lakes on the northwest. The steep-sided depression which contains Avalanche lake, Lake Colden and the Flowed lands runs also parallel to it but is less extended. The same is true of the precipitous pass northwest of Pitchoff mountain. In the extreme southeastern corner of the quadrangle the valley of Niagara brook with the wonderful and precipitous escarpment of Niagara mountain, serves to further emphasize these great northeast and southwest lines of faulting, which are the chief structural features of the quadrangle. The lines of faulting are not always single. In the summer of 1915 H. L. Alling was able to demonstrate the double character of the northeast fault below the Lower Ausable lake. Study of the map will show two valleys, separated by a narrow ridge and each occupied by a brook. Two parallel faults are responsible for the depressions and one has produced a “rotten stone quarry” for macadam at the foot of the lake. At another point much secondary calcite has developed in the sheared and brecciated rock. The crushing of the country rock along the faults and the subse- quent staining of the feldspars red or reddish brown by infiltrated iron salts, sometimes give the strongest impression to the observer that a red granite intrusive mass is before him, and one that is dif- ferent from the wall-rocks. In a number of instances the writer has been puzzled by these appearances but has in the end concluded that they were secondary. In smaller but still impressive gulches minor fractures are also brought out. One which is a favorite and easily accessible by walking from the Keene valley, is found in the northeast prolongation of the depression between Roosters Comb and Snow mountain. The gulch is so small as not to be shown on the map. It is known as Wash- burn flume, and is a narrow, precipitously walled trench, with sides as true as masonry and 14 miles long. On the road which runs southeast from the Keene valley along the course of Beede brook to Chapel pond (Chapel pond road), and at the first strong rise above the valley, there is a rock cutting in greatly decomposed anorthosite, which happens at this locality to Plate 22 Photograph of a relief map of portions of the Mount Marcy and adjacent quadrangles. The rectilinear character of the topography is well brought out. GEOLOGY OF MOUNT MARCY 57 include a huge slab of Grenville gneiss. Two strongly marked faults are exposed with crushed and decomposed rock between well-defined . walls. The master-fault strikes N. 67° W. and has a dip varying from vertical to 55° south. A smaller fault strikes N. 57° W. and is nearly vertical. A minor sheeting is also developed in a northeast direction. The first-named fault runs very true with the general course of the valley and pass containing Chapel pond. Although now at one side of the stream it was probably influential in directing the original trend of the valley. The very marked northwest and southeast courses of the minor brooks give good ground for infer- ring many other lines of crushing and weakness in this direction, and the pinched and sheeted rock exposed in numerous cascades corroborates their existence ; but the et structural breaks are north- east and southwest. The very peculiar and right-angled relations of the drainage lines led Prof. A. P. Brigham, from a study of the maps of the Mount Marcy quadrangle and its neighboring ones to the east, southeast and south, to describe them and give the name “‘trellised drainage ” to them.1 The name is appropriate and descriptive. This particular area furnishes its best illustration. The bedrock projects so gen- erally in the higher mountains that the mantle of glacial drift has not sufficed to divert the drainage from the lines of structural weak- ness and superimpose a new system, not dependent upon them. While the writer is convinced that these peculiarities of the drainage are primarily due to fault-lines, and that a great number of other faults exist, than those plotted on the map; yet only those have been indicated by a special symbol which seemed so well demonstrated by crushed zones and by pronounced escarp- ments as to leave little room for doubt in the mind of an observer. The northeasterly lines have been so often occupied by the basaltic dikes, which are regarded as Precambrian, that the faults themselves, if this assumption of the age of the dikes is true, must be still older than the dikes. Areal distribution of the several formations. The Grenville is chiefly in the northeastern border of the quadrangle. It is best developed on both sides of the East branch, but is greatly cut up by the intrusives. Some prospecting pits have disclosed the lime- stones west of Owl’s Head peak. There is also the included lime- stone southeast of the Cascade lakes. If the interpretation of the 1 Brigham, A. P., “ Note on Trellised Drainage in the Adirondacks,” Amer. Geol., 21:219, 1808. 58 NEW YORK STATE MUSEUM dark rocks in the valley of Johns brook, and in the bed of Roaring brook near the trail to the summit of Giant and at many other cited places, as included, and impregnated Grenville gneiss, is correct, we have these various outlying fragments. Other cases are known on Baxter, Gothics, Rooster Comb and other peaks, while probably many additional instances of the same exist and may from time to time be observed as fires or floods expose ledges not visible in former years or in localities unobserved as yet. The exposures are of limited extent and may be missed in the wooded areas. An exposure of the Grenville of a very characteristic sort, con- stitutes the extreme northwestern hill of the quadrangle and extends into the Santanoni sheet to the west. Limestones, quartz-diopside schist, rusty gneisses and even quartzite, if we cross the border a short distance, are all present. The anorthosites cover almost all the quadrangle. They are the predominating rock of this core-area of the mountains. They are less in relative amount in the surrounding quadrangles. In the Lake Placid and Ausable areas in the north and northeast, the geology is more complex. The syenites are developed along the extreme northern border and project southward into the valley of the East branch for about 2 miles. They are strongly gneissoid and to what extent Grenville gneisses of similar mineralogy may be mapped in with them, it is impossible to say. The mineral compositions of these two approach each other so closely that despite microscopic work the writer has often been puzzled. Dark green rocks, consisting of microperthite, augite, hornblende and sometimes hypersthene have been mapped as of the syenite series, even though having varying amounts of quartz and showing gneissoid foliation. Differences of opinion might easily arise regarding them; the more naturally because the syenitic rocks favor the limited area containing the Grenville limestones. Of the undoubted basic gabbro series, we have discovered only the two exposures of gabbro-syenite; the great dike at Avalanche lake, and the one to the northwest of it at the entrance to Indian pass in the edge of the quadrangle. In both cases the exposures are dikes. The basaltic dikes are widely distributed. The following tabula- tion will best describe them. The table brings out the fact that all but the two camptonite dikes in the Ausable river, follow the north- east fault-lines. The two camptonites run east and west or nearly so. The thickest dike is 9 feet. Where marked by an asterisk, they have been microscopically determined. GEOLOGY OF MOUNT MARCY 59 LOCATION BEARING THICKNESS VARIETY Pass northwest Pitchoff mt................. N. 58° E.. 60° E.| 2ft.......... Diabase Opposite Cascade Lake Hotel............... Northwest...... 6 ft. and small h branches. ..| Diabase* - East branch Ausable river. Northern edge of tlarcinarm le etal are) a VA ay bois) a8 fe aayal ila tl N. 75° W.90°...| 5to6Oft...... Camptonite* ; : Band iWiilOo sy aahtet ne ieee Camptonite* Brook bed west of Weston mine; 2 dikes. .... N. 55° E. 90°...| 3 ft.;9 ft..... Diabase Southeast side of Baxter mt............... INAS HE SOOn tee neEbe ental Diabase _ High Falls, on trail to Indian pass.......... ING GOI COT yall Sytlao saws Diabase North slope of MacIntyre mt. half mile below RiebaavaNTia, 6) emicolmtinte CLO DAAC SET eee ere an: INV e7O couse mitt. /Olimeaneaels Diabase West side Table Top mt. Marcy trail...... IND AS OO Tae | aribe aa eran llys Diabase Johns brook below Ore Bed brook; 3 dikes...| N. 27° E.; N. 67° i E.; N. 62° E..| 1 to 3 ft..:... Camptonite* Northwest slope Wolf Jaws above Johns brook; SRCIISES BriersVsfaeet ls Sates Saeiete hone ciate s N. 45° to 60° E..] 1 to 4 ft. 6in..| Diabase East side Rooster Comb mt................ INE Oy cee Uncertain. ...| Diabase Hlowedulandsre esate. Patek va ected wa oe N. 65° E. 90°...] tto2ft...... Diabase Mntcliernpital em eny re aitenp cum ucdeiiaveparatel oval anole INFRA DG os ace Epa ta Siilns tts le Diabase East branch, 2 miles southwest Ausable Club..| N. 34° E....... ZtONBNe beeen are Diabase* Noonmark trail; 2 dikes................... N. 65° E. 90°...| tft. 3in...... Diabase* INV OS SPE. (Oral. |) Once aero rane Diabase* Undoubtedly there are more dikes in the quadrangle, some of which may be noted by other observers from time to time. Of those recorded, all are in the northern two-thirds of the area. 6 ECONOMIC GEOLOGY; MINERALOGY Economic geology. With the passing away of the old-time forges, the small mining industry ceased as well. The only iron - mines of importance were the Weston mines, which have been described in detail on pages 22-27. They are unique in Adirondack geology in supplying ore from deposits in limestone walls, and are. believed to be due to contact metamorphism. In the syenitic gneisses in the slopes between Owl’s Head peak and Keene Center, but just beyond the edge of the Mount Marcy sheet, an opening was made years ago on a narrow body of lean ore, locally known as Rogers ore bed. Much hornblende was associated. The exposure seemed to be a basic streak in the syenitic gneiss. Magnetite is known in Cascade mountain near the included and metamorphosed limestone described on pages 17-20. Only a small amount was ever blasted from the steep precipitous front. The name Ore Bed brook for the tributary of Johns brook would suggest an ore-body, and of its existence stray statements have been heard; but personal search according to directions failed to locate the prospect. One would anticipate titaniferous ore from the local geology. 60 NEW YORK STATE MUSEUM The writer’s assistant, Charles H. Fulton, noted a narrow lenticu- lar streak of supposed ore about 400 feet below the summit of Moun: McComb, where it had been exposed by a great landslide. A thin section of it revealed about four-fifths hypersthene and .one-fifth magnetite, presumably titaniferous, as the country rock is anorthosite. In the improvements of the roads which have been carried out in the northern portion of the quadrangle, green syenite has been broken for macadam, in the northwest foot of Baxter mountain. On the south side of Baxter mountain about a mile east of the East branch a broad decomposed zone of faulted and crushed anorthosite has been dug for roads for many years. It is known as Beede’s rotten stone quarry. Abundant rocks in the boulders and ledges are every- where available for highway work. In the days of the forges limestones was somewhat quarried, and one or two ledges have been opened in old times in the northeastern portion of the area. At present, however, there is no call for it. In mineral resources the area is, so far as known, not important. Mineralogy. Barite. A vein of crystalline barite has been observed by H. L. Alling crossing the portage trail midway between the two Ausable lakes. Its strike is approximately N. 30° W. and its thickness is 5 to 8 inches. It is creamy buff in color. The wall- rock is anorthosite. Under the microscope the barite shows evidence of crushing, and contains minute augites and magnetites. The specific gravity was roughly determined at 4.35. It is of interest to note that an analysis of pyroxenic anorthosite from Elizabethtown, by W. F. Hillebrand,* yielded BaO, 0.05 per cent. Calcite in coarsely crystalline cleavage pieces is to be found in the ledges of Grenville limestone and especially in the dumps of the old Weston mine. Diopside in beautiful, green, rounded crystals is disseminated in the included mass of Grenville limestone opposite the Cascade Lakes Hotel. It is described on pages 109, 20. Garnet is abundant at the Weston mine, and in the contact zones. In the latter it is a salmon pink color, when observed in thin section. It has not been observed in well defined crystals. An analysis is given on page 21. Hedengergite, the iron-bearing pyroxene, was determined by Max Roesler in connection with the garnet reaction rims. Hypersthene is occasionally met with in fairly coarse masses in the anorthosite. An analysis is given on page 31. 1N. Y. State Mus. Bul. 138, p. 36. 4 i ; or at bee GEOLOGY OF MOUNT MARCY 61 Labradorite is universal in the anorthosite. When crushing and granulation have not destroyed the larger crystals, beautifully stri-. ated cleavage fragments may be obtained. Occasionally the char- acteristic play of colors may be seen. Magnetite in massive form may be found in the dumps ot che old Weston mine, and at the other small openings. No well-defined crystals have been met. Orthoclase, besides being a constituent of the syenites, appears in an occasional pegmatite vein. One such vein was observed by C. H. Fulton on the summit of Mount Porter. W ollastonite of pearly, fibrous character was opened by blasting a ledge in 1909 in road improvements on the east side of the East branch about one-fourth of a mile south of the edge of the sheet. It was a component of a small contact zone apparently produced by syenite on Grenville limestone. The amount was not large. 62 NEW YORK STATE MUSEUM GLACIAL GEOLOGY BY HAROLD L. ALLING Introduction The crystalline rocks of the Adirondack quadrangles have usually received more attention than the Pleistocene geology, yet glacial phenomena of the Mount Marcy quadrangle are so striking that they can not fail to impress the summer visitor or resident. When the terraces and beaches of former but now extinct lakes are ttaced and their various outlet channels are located and correlated, it is possible to decipher a history of glacial times that is full of interest. The responsibility for the presence of several groups of glacial lakes must be ascribed to the damming of valleys by the ice sheet. In the two parallel valleys, the Keene valley, with which we have much to do, and the Elizabethtown-Pleasant valley to the east, the drainage was northward, but the ice body, preventing the normal escape to the sea, flooded these depressions with standing waters. Each definite pause assumed by each level was controlled by lateral outlet channels. As the ice retreated northward, lower and lower spillways were opened, with a consequent lowering of the waters, initiating lakes of lower altitudes. In order to follow the succession of the glacial waters in the Mount Marcy sheet with any satisfaction it is necessary to describe briefly some of the glacial phenomena of adjacent quadrangles, but such excursions will be limited to features of the lakes that in whole or in part once covered portions of the quadrangle. Although positive evidences of multiple glaciation in the Adiron- dacks are not forthcoming, pre-Wisconsin glaciation in Pennsyl- vania, New Jersey and New England has been established so as to lead us to conclude that this area has been subjected to continental ice bodies more than once. In some of the brook valleys the depth of the drift is enormous and often a difference in the degree of weathering of different levels can be detected. In the valley which extends from the slopes of the Cascade-Porter mass northeastwardly to the East branch of the Ausable, the thickness of morainal material is certainly not less than 200 feet and is one of the most promising deposits harboring evidence of pre-Wisconsin ice action within the quadrangle. All evidence points to the conclusion that at the maximum extent the Adirondacks were completely buried by the ice, which spread ‘ GEOLOGY OF MOUNT MARCY 63 Fig. 7 Sketch map showing location of the Mount Marcy quadrangle and the three drainage basins; the St Lawrence, Champlain, and Hudson rivers 64 NEW YORK STATE MUSEUM over the major part of the State, reaching as far south as New York City. In order to provide a sufficient gradient for such an expanse of ice the surface of the ice that moved over the quadrangle has been estimated to have been from 8500 to 12,000 feet above sea level1 To this enormous load upon the land surface is attributed the well observed phenomenon of deformation, to which we shall return later. Movement Two occurrences of glacial striae have been noted in the quad- rangle; they are situated beside the highways in the valley of the East branch of the Ausable river. The direction of both of these striae is due south, indicating that the topography was the controlling influence affecting the course taken by the waning ice lobes lying in the valleys. The more general direction of the ice flow would be shown by striae on the mountain summits, but their records have been destroyed by weathering. It is believed, however, that the ice that covered the quadrangle flowed southward with a slight deviation to the west. Erosional Work The residual soil resulting from weathering during interglacial periods was completely removed by the ice, the mountains smoothed and their contours subdued. This effect of ice action is recorded in the comparatively fresh condition of the rocks on exposed ledges, and in the dignity of the round dome of Marcy probably due to glacial erosion. The many amphitheaters and little rocky pockets on the mountain sides are due, in all probability, to the plucking action of the ice. These cirques have been attributed to the combined work of the continental ice bodies and to local glaciers.” “An amphitheatre with steep walls . . . is a favorite form for the Adirondacks, being well shown on .. . the Gothics,’* the Cascade-Porter massif, Big Slide, Haystack and Noonmark. Occasionally small ponds are located on the southern or lee side of the mountains, apparently occupying basins plucked out by the ice. Lost pond in the south- western corner of the Ausable sheet, the pond on Clements moun- tain in the quadrangle to the north, and the Giant Washbowl and Dipper are examples. 1 Fairchild, H. L. Bul. Geol.. Soc. Am., 24:136. 1913. After Shackleton. 2 Ogilvie, I. H., “Glacial Phenomena in the Adirondacks,’ Jour. Geol., 10:406. 1902. Johnson, D: W., “Date of Local Glaciation in the White, Adirondack, and Catskill Mountains,” Bul. Geol. Soc. Am. 3Kemp, J. F., N. Y. State Mus. Bul. 21, p. 63. 1808. Plate 23 Glacial boulder, northeastern portion of the quadrangle. The rock is anorthosite, and is about 12 feet in diameter. a GEOLOGY OF MOUNT MARCY 65 The major fault-line valleys furnished passes for ice tongues to push through. The slopes were smoothed and carved into U-shaped defiles. Such phenomena are observed in the Cascade fault-line’ valley, and the valley holding the Lower Ausable lake, which were blocked by crescent-shaped moraines deposited upon the retreat of the ice lobes. The occurrence of glacial boulders is quite common, some of which appear to have been transported from great distances, while others can be traced to parent ledges in the neighborhood. Rounded boulders of “ Potsdam ”’ quartzite have been noted all over the quad- rangle. Large irregular slabs of Potsdam sandstone and quartzite are encountered in some of the brook valleys where the drift is abnormally thick. In the brook valley where the Weston mines were located irregular nonglaciated flagstones were found in such numbers as to strongly suggest that a ledge of the Potsdam existed there before the ice invasion broke it up. Similar occurrences in the Eliza- -bethtown* and Lake Placid * quadrangles together with outliers ? point to the conclusion that the Adirondacks were more or less com- pletely mantled by the Potsdam. Dr D. W. Johnson suggested to the writer that the sawtooth shape of the Niagara mountain block fault in the southeast corner of the quadrangle may have been pre- served by the deposit in it of a ledge of Potsdam sandstone that was subsequently eroded and destroyed by the ice. Doctor Kemp reports that no remnant was found. Constructional Work There is little true morainal material, for most of it has been modified by water ;° the movement of the ice during the maximum advance having, evidently, been too vigorous for deposition and the material that was deposited as the ice retreated having been sorted by the waters of the glacial lakes. ‘The recessional moraines appear to be largely confined to the fault- line valleys, being formed by the ice tongues as they withdrew from the narrow defiles. At the southwestern ends, in the broad val- leys, the rate of retreat was slow and moraines were formed; but 1Ruedemann, R., N. Y. State Mus. Bul. 138, p. 62. 2 Alling, H. L., N. Y. State Mus. Bul. in press; Bul. Geol. Soc. Am., 27:050. I916. 3 Miller, W. J., N. Y. State Mus. Bul. 182, p. 44. 4 Cushing, H. P., N. Y. State Mus. Bul. 115, p. 495. > Ogilvie, I. H., Jour. Geo., 10 :406. 66 NEW YORK STATE MUSEUM in the narrow valleys the melting of an equal amount of ice would ~ produce a much more rapid recession, giving but little opportunity for the deposition of material. Again at the northeastern ends of the passes the ice tongues paused long enough to deposit another series of moraines. Such recessional moraines blocking both ends of the Cascade lakes fault-line valley have resulted in the basin within which the lakes are now situated. Originally but one lake occupied the depression. A similar group of moraines act as a natural dam retaining the waters of the Lower Ausable lake. Man has come to the aid of nature and reinforced and heightened it. It is very likely that only one lake lay in the Ausable lake fault-line valley before the accumulation of the delta sands of Shanty and Haystack brooks. Doctor Kemp has already called attention to the morainal dam con- fining Chapel pond. This long narrow ridge is an esker; the glacial deposit of a stream flowing beneath the ice. Another esker is excel- lently well displayed beside the state highway from Keene to Eliza- bethtown half way up “Spruce hill.” It can be traced for nearly one-fourth of a mile. The preglacial drainage has been modified by glacial material of one kind or another in several localities. An excellent example of stream diversion is south of the town of Keene on the northern boundary of the quadrangle, in the East branch of the Ausable river. In this comparatively broad valley we note an unnamed hill, around the two sides of which the two highways leading to Keene valley circle. To the west of the hill the present river rushes between steep walls of syenite complexly involved with various Grenville rocks, experiencing rapids and falls. It is clearly a postglacial chan- nel and is one of the beauty spots in the quadrangle. On the other side of the hill the preglacial channel is plainly visible although now blocked by sands of a lateral delta. The accompanying map shows the probable course taken by the branch before the invasion of the ice. Farther upstream a similar state of affairs is suspected, but not so easily proved. Back of the Ausable Club (Beede on the map) the present river leaves the fault-line valley, following a recently formed gorge in anorthosite. One-half of a mile to the east the topography and the sand plains seem to indicate that the preglacial channel fol- lowed a direction across the bedrock, now under the eroded surface of the terraces of the Saranac glacial waters, the probable course being indicated by the road in its circuit around the golf links. GEOLOGY OF MOUNT MARCY 67 Local Glaciation The study of lateral moraines in the brook valleys, the poorly developed and incipient cirques on the mountain slopes and hanging. tributary valleys has convinced the writer that local glaciation has occurred in the Adirondacks. In 1916 Doctor Johnson demonstrated to the satisfaction of the writer that such action took place after the withdrawal of the continental ice sheet.* In the cirque on the eastern slope of Esther mountain, a portion of the Whiteface massif, in the Lake Placid quadrangle, we found the remnant of a local moraine convex down stream. This cirque valley slopes northeast offering a favorable opportunity for the continental ice to force a tongue into it and to deposit a recessional moraine; but this would have a crest declining southwest, while that found has the opposite inclina- tion. In the valley of Slide brook lateral moraines are situated on both sides of the stream and appear to assume similar positions and forms. Rich * has shown that local glaciers existed in the Catskills which is a region less likely to support local glaciers than the Adirondacks, thus lending support to the writer’s contention. Extinct Glacial Lakes There are extensive sandy plains within the quadrangle that undoubtedly owe their origin to the continental ice. Unless shore line features and outlet channels can be found to show that they are of lacustrine parentage they are regarded as outwash plains formed in front of the melting ice, the débris being swept into the valleys by the glacial streams. Such plains are often dimpled with ice-block kettle holes in contrast to lake flats and bottoms. The great sand plain of the South Meadows country, in the northwest corner of the quadrangle, is an excellent example of this type of glacial deposit. When first observed it was regarded as an outwash plain but rem- nants of concordant beaches were found on Scotts Cobble and Pitchoff mountain to question such interpretation, and thus the plain is explained as a glacial lake deposit. It is quite reasonable to believe, however, that it may have been an outwash plain modified _ 1Johnson, D. W., “Date of Local Glaciation in the White, Adirondack and Catskill Mountains,” Bul. Geol. Soc. Am. 28 2543-552, 1917 2 Rich, John L., “ Notes on the Physiography and Glacial Geology of the Northern Catskill Mountains,” Am. Jour. Sci., 39 lv, Feb. 1915, p. 154; “Local Glaciation in the Catskill Mountains,’ Jour. Geol., 14:113-21, 1906; “Local Glaciation in the Catskill Mountains,’ 29th Annual Meeting, Geol. Soc. Am., paper 12, Dec. 27, 1916. Abstract Bul. 28 :133, 1917. 68 NEW YORK STATE MUSEUM and smoothed by lake waters. The Boreas ponds — Elk lake areas in the southern portion of the sheet are similar. Conditions Favorable for Glacial Lakes in the Region A number of important factors favored the formation of several series of local glacial lakes in the east-central Adirondacks which formerly existed in the area covered by this bulletin. Among the conditions we note: (1) northward draining valleys, sloping toward and blocked by the ice lobes; (2) the complete isolation of such valleys by mountain ranges; and (3) the presence of a huge ice ring that completely surrounded the Adirondack highlands impounding vast quantities of water. The Mount Marcy quadrangle was situ- ated close to the northeast rim of this ice ring. The large amount of sand and gravel for the formation of deltas, terraces and beaches, makes possible the recognition of the different lake levels in the valleys. The cause of the great quantities of sand is discussed later on. . As noted above, Taylor * was one of the first to describe a number of glacial lakes in the east-central Adirondacks, although he did not attempt to separate and correlate the different levels with any great care. A year later Kemp’ noted two or three sets of deltas in the Keene valley. In dealing with the glacial lakes the writer has for convenience classified them in three sections: (1) the western section, which included the area around Lake Placid, west of the Wilmington notch; (2) the eastern section, or the Keene valley division in the valley of the East branch of the Ausable; and (3) the Elizabethtown- Pleasant valley group. The last section does not come under discus- sion here. Upper Series Western Section As the ice sheet began to wane, the highest peaks of the Adiron- dacks were the first to be uncovered, playing the role of islands in a sea of ice® (see figure 8). Slowly these islands became larger, sur- rounded by a growing accumulation of water impounded by the ice. These waters found escape over the ice to the south and eventu- ally passed to Susquehanna drainage. This progress of melting was continued until entire mountain ranges were exposed. 1Taylor, F. B., “Lake Adirondack,’ Am. Geol. 19 :392-06. 1807. 2Kemp, J. F., N. Y. Mus. Bul. 21, p. 60. 8 Fairchild, H. le Ne Wie State Mus. Bul. ao pl. II. GEOLOGY OF MOUNT MARCY 69 The South Meadows lake. The highest definite level recognized by the writer in the Mount Marcy quadrangle is the South Meadows lake, so named from the remnants in the South Meadows country. About one-fourth of the area covered by the lake is situated in the Mount Marcy sheet; the Lake Placid, the Saranac and Santanoni quadrangles coming in for equal shares of the rest. It is believed that the ice consisted of three lobes; one covered the greater portion of the Saranac quadrangle, the second lobe was fed through the Fig. 8. Map showing the preglacial channel of the East branch of the Ausable river south of Keene. Light lines, contours, 100 foot interval; heavy continuous lines, streams; heavy broken lines, preglacial channel; straight line near top, boundary between Mount Marcy and Lake Placid quadrangles. North is at the right hand side of figure. narrow depressions to the east and west of the Whiteface-Esther- Wilmington massif and covered the territory where Lake Placid now lies; the third and most eastern lobe, here considered, completely filled the valley of the East branch of the Ausable river, including the Keene valley. The South Meadows lake was of irregular shape, some 10 miles long and wide, containing a number of islands, among which Mount Jo and Seymour mountain can be mentioned. Its outlet has not, as yet, been definitely established, but a very probable one is offered as follows: It begins at the swamp just south of Alford mountain in the Santanoni quadrangle on the Essex-Franklin county O NEW YORK STATE MUSEUM N boundary line (altitude 2105.5 feet, 2020 on the map), it passes westward through the narrow pass (altitude 1980 feet) directly south of Van Dorrien mountain to Blueberry pond. Continuing westward into the Long Lake quadrangle, on the boundary between the two maps, it turns to the southwest and passes three-fourths of a mile south of Palmer brook. When within a mile of the Racquette ) il —— 7 Fine te TT RENEE TI TT SLA SL —— a, 2 WP EEE, (DMM MROET aS SE CS IT EEE WES TIES SS EEE (SEE NS STS TS TS = Se for + MILES oe MAA Fig. 9 The glacial lake succession in the Mount Marcy and adjacent quadrangles. Stage 1. The South Meadows lake, altitude 2210 to 1960 feet. river the course turns directly south over Brueyer pond. This river course is a mere suggestion, as actual field work has not been under- taken in the rugged and inaccessible Santanoni quadrangle. Prob- ably the waters flowing in this channel did not form a single river but consisted of a chain of lakes and ponds. A number of unmistakable beaches exist on the shoulders of the Plate 24 Beach of glacial lake South Meadows, altitude 2172 feet, on the southern shoulder of Sentinel range, Mount Marcy quadrange. L. Alling, 1916 photo. 13h, GEOLOGY OF MOUNT MARCY WA Sentinel range and on Scotts Cobble, on the northern edge of the Mount Marcy sheet. One series ranges from 2123 to 2172 feet in - altitude.* These figures, in all probability, represent the water levels during the early stages of the lake. Sand plains with altitudes close to 1960 indicate that the lake level was undergoing constant lowering. It is suggested, as a reasonable explanation of this lowering, that as the small ice lobe 3 miles east of the highest peak of Ampersand mountain retreated, it allowed escape through the channel of the East branch of Cold brook and then south to the Van Dorrien pass which held the waters to 1980 feet. The fault-line valley containing the Cascade lakes was probably blocked by a glacial lobe and morainal material which prevented escape to the east; the drainage of the South Meadows being to the west as suggested above. Western portion of Upper Lake Newman. With the gradual retreat of the ice and its constant shifting position, new and lower outlets were uncovered. Succeeding the South Meadows lake the western portion of Upper Lake Newman” was ushered in. As the remnants of terraces and sand plains of this level are rather indefinite in character and the range of the elevations of the surfaces is con- siderable (1800 to 1895 feet), the writer is not unmindful that stream. filling forming an outwash plain from the glacier may be a logical explanation, yet in view of the fact that the sand plains are found over a considerable area confined within these limits, they are regarded as representing a series of lake bottoms formed by a lake (or series of lakes) whose level: was experiencing periodic lowering due to the downcutting of the controlling spillways. These spillways. may have been over the ice itself or a series of outlets controlled by ledges of rock. Unfortunately, however, the outlets of the lake are not positively known but in all probability the drainage was to the west, similar to that of the South Meadows lake. This lake probably covered more territory than its predecessor but not so much of the Mount Marcy sheet, being largely situated in the Lake Placid and Saranac quadrangles. The portion of the lake situated within the Marcy map assumed a four finger-shaped body of water. Ice lobes lay to the east of the Wilmington notch in the valley of the East branch of the Ausable preventing ahy connection between the eastern and western portions of the area. 1 Determined by a surveying aneroid barometer, corrected for temperature of the air and checked against a barograph, hence as accurate as this method permits. 2 Alling, H. L., N. Y. Mus. Bul. 207-208. ‘1910. 72 NEW YORK STATE MUSEUM The best preserved terraces of the Upper Lake Newman were found in the neighborhood of John Brown’s grave just over the northwest edge of the sheet, along the West branch of the Ausable. The name of the lake is derived from the town of Newman, the terminus of the Delaware and Hudson Railroad, where well-pre- served levels occur. NR Ni UN Fig. 10 The glacial lake succession in the Mount Marcy and adjacent quadrangles. Stage 2. (1) Upper Lake Newman, altitude, 1895 to 1800 feet. (2) The Keene lake, altitude, 2023 to 2000 feet. The main ice dam that retained the lake was situated for a time near the southern edge of what is now Lake Placid. In the vicinity of John Brown’s grave, beaches show a complete separation of Upper Newman from the succeeding lake, Lower Newman; the upper series ranging from 1800 to 1820 (one well-marked level at 1806.5 feet) while the lower group vary from 1740 to 1780 feet. GEOLOGY OF MOUNT MARCY 73 Eastern Section The Keene lake. During most of the life of the western portion of Upper Lake Newman, the ice lobe in the valley of the East branch of the Ausable was retreating northward and allowed a growing body of water to accumulate in the Keene valley. This body of water, named the Keene lake, left terraces high up on the valley walls, especially in the brook valleys where the present streams have bisected them. The sands on the East hill, near Hurricane Lodge, at 2000 feet altitude, were probably deposited at this time. The lake filled Keene valley and thus was located mainly within the confines of the Mount Marcy sheet. The outlet is at present believed to have been south through the double fault-line valley in which the Ausable lakes are now located into standing waters in the northern half of the Schroon Lake sheet. The two passes to the east, the Spruce Hill pass, and the Chapel Pond pass, although much lower than the surface of the water, were apparently effectively blocked by lateral ice lobes forced into them from the east, being tongues of the ice body occupying the Elizabeth- town-Pleasant valley, thus making escape to the east impossible. Studies of these two passes lead to the above conclusion. The eastern end of the Wilmington notch was uncovered by the retreat of the ice that dammed the Keene valley, furnishing a connec- tion with the western portion of the area, permitting the waters in the valley of the East branch to fall to the level of Upper Lake Newman. During the life of the Keene lake the area south of the Upper Ausable lake was flooded; an ice dam lay in an east and west line across the upper portion of the Schroon Lake quadrangle.* As this ice wall melted the waters south of the divide were separated from the Keene lake so that the Boreas-Elk-Clear pond section became a distinct glacial lake, which in turn may have been subdivided into the Boreas lake and glacial Elk lake, while the drainage of the remain- ing Keene lake flowed into the Boreas lake through the pass east of Moose mountain, until extinguished by the formation of Upper Lake Newman. Upper Lake Newman. The life of the eastern portion of Upper Lake Newman was probably relatively short compared with that of the western area, for the terraces are very indefinite and the separa- tion of the benches into an upper and a lower series does not exist, or at least can not be demonstrated. Thus soon after the establish- 1 Pairchild, H. L., N. Y. State Mus. Bul. 160, pl. 12. NEW YORK STATE MUSEUM 74 fluent with the western portion situated in the South Meadows country, and in the Lake Placid and Saranac quadrangles, the outlet was changed, and perhaps rapidly deepened by the additional volumes of water from the eastern section, so that the waters fell to the level ment of Upper Lake Newman in the Keene valley, which was con- of Lower Lake Newman. POR SSS SSS Le SSB, Bg EN! a) aS hse y and adjacent Lower lake Newman, altitude, 1740 to 1780 feet. as) The glacial lake succession in the Mount Marc Stage 3. Fig. 11 quadrangles. Eastern and Western Sections This lake was of still greater extent than Lower Lake Newman. Its northern, and espec- -described bodies of water. any of the above , extent and boundaries are still to be studied and determined. Our present knowledge, however, would lead us to conclude that the valleys occupied by the West and East branches of ially its northwestern a : a GEOLOGY OF MOUNT MARCY 75 the Ausable river were flooded, the connecting link between the two being the Wilmington notch. This is inferred by the fact that deltas and terraces at similar heights were found to the east and west of the notch. How else could the waters of the two areas have been confluent? These waters thus flooded the Keene valley, the South Meadows country, the area occupied by Lake Placid today and the greater part of the Saranac quadrangle. Terraces are located on _ East hill and the hill traversed by the Keene-Cascade Lakes road. The outlet of Lower Lake Newman is not definitely known but according to the present data it seems likely that it was to the west. It is possible, though regarded as very unlikely, that the Chapel Pond pass became an outlet at the close of this period, changing: the drainage to the east. The South Meadows, and the two Newman Lakes, probably had outlets to the west; the Keene lake drained south; but the succeeding lake (or group of lakes) had drainage to the east. Saranac glacial waters. The series of sand plains, terraces etc. that come under this head were recognized by H. P. Cushing * in the Saranac region, in what is generally known as the lake belt. These levels have such a wide range of altitude, 1540 to 1660 feet, that they must have been produced by a series of glacial lakes, or have been deposited by aggrading streams which no longer exist, or by a com- bination of both. Doctor Cushing is of the opinion that: “ these sands were probably deposited as deltas in a large irregular, shallow lake formed back of the ice tongue which occupied the ‘lake belt’ during its slow retreat north, the material being furnished by the subglacial and englacial streams flowing into the lake at the ice’ margin.” ? As nearly two-thirds of the Saranac sheet exhibits terraces and sand plains of the higher levels, it is not inappropriate that the term | Saranac glacial waters should be applied to them. . The area covered by the Saranac glacial waters varied so much during its existence that it is difficult to give the precise limits within which it lay. During the early stages it was chiefly located in the Saranac quadrangle, while during its closing episodes the Lake Placid sheet came in for its share, the southern: ends of the lake levels extending into the Mount Marcy area. The general character of the terraces is that of gentle sloping plains on the mountainsides without any prominent shore line feat- 1.Cushing, H. P., “ Recent Geological Work in Franklin and St Lawrence Counties,’ N. Y. State Mus. Ann. Rep’t, 1900, p. 20. 2Ops cite 76 NEW YORK STATE MUSEUM ures, except in a few localities in the Lake Placid sheet. The indefinite nature of nearly all the sand plains strongly suggested the work of aggrading glacial streams, but with the discovery of a series of. remarkable glacial outlet channels in the center of the Ausable quadrangle whose spillways correlated with almost mathematical ae 94 VA] 0029697 ay ay fv EO Go 1) ee SS ph WH) __ Hi = | EAS Hk — ae SN Jee = Rageacaaascaacaaeaeagie — AV — semen ENGEL CELA OHH! =4 oat edzauate = O 5 10 15 Hie = SSS =e SS cy SI MILES os - Oy tS RS AGUeGe Fig. 12 The glacial lake succession in the Mount Marcy and adjacent quadrangles. Stage 4. Lower stages of the Saranac glacial waters, altitude of particular phase here represented, 1500 feet. Total range of Saranac glacial waters, 1450 to 1660 feet. exactness with the beaches above mentioned the glacial lake origin of the Saranac glacial waters became clear. Here we must depart from the confines of the Mount Marcy sheet to understand the history of these conspicuous levels.t 1 Alling, H. L., “ The Glacial Lakes and Other Glacial Features of Central Adirondacks,” Bul. Geol. Soc. Am., 27:658, and fig. 1. 1916. GEOLOGY OF MOUNT MARCY id Beginning on the southern slopes of Ellis mountain, in the town- ship of Jay, a long glacial channel extends south for a distance of some 10 miles with a dozen side outlets to the east. The lake entrance to this channel was south of Ellis mountain at the northern end of the South gulf as this north and south fault-line valley is locally called. The controlling spillways were regulated by the ice lobe that lay to the east. Thus as the ice retreated it permitted escape _ first by the most southern side-outlets which represent the outlets of the early stages of the Saranac glacial waters; while later lower spill- ways were opened farther north with a consequent lowering of the waters. In several of these channels abandoned falls and cataracts were found, which, together with correlation of the elevations of the outlets and minor breaks in the sand plains, furnish positive evidence of the origin of these levels. The chief cause for the indefiniteness of the levels and the lack of . shore line features is attributed to the fact that the ice was the bar- rier controlling the spillways in many cases. Many one-bank chan- nels exist showing unmistakable evidence of the rapid lowering of the waters. Eastern Section St. Huberts lake. At a lower altitude than the Saranac water levels there are scattered terraces of indefinite and sloping character situated at 1300-1340 feet elevation. They are subordinate in interest to the preceding levels as well as to those described below. There is a small but finely developed terrace at the head of Keene valley at 1300 feet. The level surface is now used as a baseball diamond. Taking this as a starting point the other terraces fit into the general scheme and thus there is the possibility of a lake level at this altitude in the series that once flooded portions of the Mount Marcy quadrangle. The most prominent remnant left of the St Huberts lake is on the northeast slopes of Owls Head now traversed by the Keene-Cascade highway, just off the northern edge of the map. Its outlet was without much doubt to the east through the gulf, south of Ellis and Bald mountains in the Ausable quadrangle, the spillways being controlled by one-bank channels which are beauti- fully shown in the woods on the southeast slopes of Black mountain. The Lower Series Confined Entirely to the Eastern Section In descending from the higher lake levels to the lower ones, the character of the terraces changes from indefinite levels of consider- 78 NEW YORK STATE MUSEUM able range to neat, clear-cut deltas, wave-cut cliffs and beaches con- fined within concise limits. No question can be raised as to the origin of many of them. They represent remains of true glacial lakes. Wilmington lake. The history of the Wilmington lake is, per- haps, the best understood of all the local glacial lakes in the east- central Adirondacks. It is chiefly confined to the Lake Placid quad- = I 7) UW aS, Y) 4 \ Fig. 13 The glacial lake succession in the Mount Marcy and adjacent quad- rangles. Stage 5. The Wilmington lake, altitude 1100 to 1157 feet. rangle, to the East branch of the Ausable river, and to the territory around the town of Wilmington but sent a southern prong into the Keene valley to the base of the Ausable Club hill. At the foot of Johns brook, especially on the western side of the valley, there is an extensive delta with an elevation of 1100 feet. ‘C161 ‘dwoay “4 ‘f Aq ydersojoyg J99J OOII ueY} sso] Al}YSTs ‘opnynye Jussotq “Ase sus JO ISEI[IA IY} JO YINOs aw ve Fey ‘Yoo1g suyof Jo OOF OY} FY “VOJSuTuI\\ SYP] JO eiop JO JULUTLOT poJIISSIC] #@ aye GEOLOGY OF MOUNT MARCY 79 Remnants are situated on the east side of the valley composed of very fine sand while the western exposures are made up of coarser materials. At the valley wall distributary channels are well shown; pebbles and boulders as large as one’s fist or larger are common. It is evident that the delta materials came from the Johns Brook valley and were deposited in standing waters by the ice-fed Johns “ river.” Fig. 14 The glacial lake succession in the Mount Marcy and adjacent quadrangles. Stage 6. The Upper Jay lake (upper phase), altitude, 1017 to 1046 feet. A number of beaches of the lake are beautifully shown on a hill a mile north of Keene, in the Lake Placid sheet. The altitude of the best developed one is 1113 feet. Farther to the northeast we find the spillway at the entrance of the gulf in the Ausable sheet at 1157 feet. The cause of these apparently nonconcordant figures is due to 80 NEW YORK STATE MUSEUM postlacustrine deformation and tilting; a subject treated more in detail on a later page. The outlet of the Wilmington lake was through the gulf and ihe southeast to cross and then south to near Elizabethtown. The escap- ing waters were forced to take such a course because of the ice lying in the valley of the East branch of the Ausable with its southern wall at Lower Jay. Another body of ice blocked the narrow valley now occupied by Trout pond. The gulf channel contains a number of Pleistocene cataracts of which the remarkably beautiful Copperas pond is the most striking example. Upper phase of Upper Jay lake. The Upper Jay lake, like its predecessor, the Wilmington lake, has left terraces and beaches that are very definite in character. One beach on the hill a mile north of Keene is 1017.7 feet in altitude while still another in the Ausable sheet is 1045 feet above tide. The controlling spillway is situated 114 miles north of Bald mountain. The part of the lake that existed in the Mount Marcy area was only 2 miles long. Lower phase of the Upper Jay lake. A lower phase of the Upper Jay lake is indicated by beaches and terraces in the Lake Placid sheet at 994 feet, and was almost entirely confined to the Lake Placid and Ausable quadrangles. The lakes that succeeded the Upper Jay lakes do not concern us as they did not occupy any portion of the Mount Marcy quadrangle. Yet for an understanding of the postlacustrine deformation the well- established levels are here listed, with their altitudes: Haselton lake, 967 feet; Lower Jay lake, 930 feet; Otis lake, 903 feet; Rocky Branch lake, 860 feet; ‘“‘ Clifford” lake, 835 feet; “ Marine level,” 646 feet. Postlacustrine Deformation and Tilting * It has been pointed out that at the maximum extent of the conti- nental ice sheet the load upon the land surface must have been tre- mendous and must have subjected the land to great compressional stress, which caused it to be depressed below its former level. Since the ice was thicker in the north than in the south the amount of deformation was greater in the northern part of the State. With the removal of the load by the melting of the ice the land has “ sprung” back, thus elevating the surface and tilting the shore 1 This subject of deformation has not yet been fully considered by structural geologists in the light of isostasy. GEOLOGY OF MOUNT MARCY 81 line features of the glacial lakes. It has been shown by Fairchild in a number of papers’ that the character of the postlacustrine uplift was a lifting in the form of a warped plane with the amount of warping greater to the north. The lines of equal uplift since the time of the marine level incline in this portion of the State west- northwest to east-southeast (20 degrees from the latitude parallels). The zero isobase passes far south of New York City. The 600 foot -isobase touches the northeast corner of the quadrangle, while the 553 foot isobase enters the sheet in the southeast corner. These figures give the total uplift for the region since the marine waters occupied the Hudson-Champlain embayment. ‘The figure for the amount of tilting for this marine plane in this region is 2.71 feet a mile taken along a north and south line, or 2.83 feet perpendicular to the isobase. Although Fairchild’s papers form a very valuable contribution to this subject, there exists some uncertainty as to the character of the uplift. (1) Was the upward movement gradual and uniform or (2) ‘was it in the nature of a wave or a series of sudden uplifts? The writer believes that the problem will be clarified by the measurement of beaches, deltas etc. situated at higher levels than the marine plain to supplement those mapped at the lower altitudes. The shore phenomena of the lakes above described afford an opportunity to determine the amount of tilt of the land surface, for they furnish a series of datum planes higher than those in the Champlain valley, which was occupied by the ice during the entire period that these lakes existed. Fairchild believes that his figures give the total uplift since glacial times. The writer feels, however, that this conclusion is based upon the state of affairs that prevailed during and after the marine stage and overlooks the shore phenomena of higher lake levels. Although accurate measurement of the amount of tilc of the lake levels of the Mount Marcy and adjacent sheets is exceedingly difficult, for the chances of error are great, the table given below would indicate that the uplift was taking place while the ice was melting from the area. 1 Fairchild, H. L., “ Pleistocene Uplift of New York and Adjacent Terri- tory,” Bul. Geol. Soc. Am. 27:235-62; “ Post-Glacial Marine Waters in Vermont,’ Rep’t of Vt. State Geol. for 1915-16. 82 NEW YORK STATE MUSEUM Deformation table ALTITUDE ——_—_—_———___——__| DISTANCE | TILT, FEET LAKE MILES A MILE (2) South- | (b) North- ern station/ern station POUL Meadowsr es. meine Giacieciumnisniers 2105. t 5 2123.0 6.5 3.7- 2uUpner Newman. sali. 4. yesh eee ane eee 1806.5 1823.5 6.0 3.52 SIINCONE Lance aie eae ci ule onan Peeve cea 2000.0 2023.0 8.0 3.48 4 LoweriNewmanye eno side ck Beek eee 5 A 1743.0 5.75 Zugi2 BP ALAMIAGIALELS Nol yo iy et oun etn ere eae I610.0 1637.5 9.12 3.2- Ou St Eicberts'ycptyes © deren s Sees HERES ORE 2 1300.0 1321.0 6.5 Sy TeV train ctor. cee reas cede is oleic hoe nk tale II00.0 1157.0 16.75 2.94 8: Upper phase Upper Jay oj. 0s thee sees bee 1017.7 1046.0 10.2 2.80 Oo Lower phase Upper lave. oonncteeniee oeaonk 993.9 1024.0 II.o 2.75 TOMEASe POM a anne coe re oo Bees ies atte 067. Sol vaniarerares Bayt Tr ower Vay wee he core ee as gee oo eee, 930; - +>.) |) bend ee P2NOUS a oe och tate hee ee oo oe Oe 0030 Se 19) Rocky ioran chased. sas ee ome 860») «> feessyeyetete aneall Ee eee eae CIE ONG Maes teats, ote, aie they a Gentoo emoerae cesiaeiers 835 20. eee 2.70 Tope Marinellevel? i cht ode tune ee eaters 646 0° | oe 2 TE Location Index to Deformation Table 1a Van Dorrien pass, one-half of a mile south of Van Dorrien mountain; Santanoni quadrangle. 1b Beach, shoulder of Pitchoff mountain; Mount Marcy quadrangle. 2a Beach, one-half of a mile north of John Brown’s grave; Lake Placid quadrangle. 2b Terrace-bench, one-fourth of a mile north of Owen pond; Lake Placid quadrangle. 3a Terrace, foot of Lower Ausable lake; Mount Marcy quadrangle. 3b Beach, foot of Lower Cascade lake; Mount Marcy quadrangle. 4a Terrace, seven-eighths of a mile west of Owls Head; Mount Marcy quadrangle. 4b Beach, one-half of a mile north of Harrietstown; Saranac quadrangle. 5a Wave-cut cliff, 3 miles north-northeast of Keene; Lake Placid quadrangle. 5b One-bank control channel, 2 miles east-southeast of North Jay; Ausable quadrangle. 6a Baseball diamond, near Ausable Club (Beede) ; Mount Marcy quadrangle. 6b Terrace-beach, 1 mile west-northwest of Keene; Lake Placid quadrangle. 7a Delta, foot of Johns brook; Mount Marcy quadrangle. 7b Spillway, Gulf; Ausable quadrangle. 8a “ Keene Hill,” one-half of a mile north of Keene; Lake Placid quadrangle. 8b “Lower Jay Hill,’ 114 miles northeast of Lower Jay; Lake Placid quadrangle. ga One-half of a mile northwest of Keene; Lake Placid quadrangle. ob One and three-fourths miles northeast of Lower Jay; Ausable quadrangle. It will be noticed that the rate of tilt decreases as one passes from the South Meadows lake to the lower altitude of Lake Haselton; the tilt of the latter appears to be the same as that of the marine plain. If any confidence can be placed in the figures it would seem that the waters below and including Haselton drained directly into the marine waters. Since the process of warping and uplift were synchronous it would appear that the total amount of uplift for the Mount Marcy quadrangle since glacial times is greater than the amount, 600 feet for the northeast corner, proposed by Fairchild. a a GEOLOGY OF MOUNT MARCY 83 Cause of the Large Amount of Material Available for the ‘ Formation of Terraces . One of the striking features of the glacial geology of the Adiron- dacks is the small amount of true morainal material’ unmodified by water” as contrasted with the vast quantities of sand and gravel in deltas, terraces etc., when compared with other districts, such as the Catskill mountains. The writer offers the following hypothesis to account for this condition. Fairchild’ pictures a vast ring of ice completely surrounding the Adirondacks, isolating them from the rest of the State. It was during this stage that the glacial lakes herein described existed. The great ice sheet undoubtedly destroyed all vegetable life in both the Adirondacks and the Catskills, but in the latter case the ice retreated northward as an irregular edge which allowed vegetable life to follow the ice in its withdrawal. This condition was not possible in the Adirondacks where the ice ring prevented much if any encroachment on the part of plants into ‘the ice deforested area. In the Catskill region the glacial drift was anchored by the roots of newly growing shrubs etc., and thus it was not easily washed by the streams into the standing waters in the valleys below, so that a large amount of the drift still remains on the slopes. On the contrary the glacial débris in the Adirondacks was not anchored and most of it has been carried down into the valley bottoms and there worked over into lake deposits. This has an important bearing upon the flora of the region and the disastrous effects of forest fires on the thinly soil-mantled mountain slopes. Summary of the Glacial Lake Succession The Mount Marcy quadrangle was situated near the northeast rim of the ring of ice that surrounded and isolated the Adirondack high- lands from the rest of the State, and thus the northward-draining valleys were blocked, preventing the escape of the vast quantities of waters which flooded the district with lakes. These bodies of water, especially at the higher levels, did not leave: distinct shore line features, for their outlets were controlled by ice lobes which caused constant or periodic lowering of their surfaces. _ The district covered by the glacial lakes here described can be - divided into two sections, the western and the eastern. In all proba- bility the western section was the first to be relieved of ice, thus 1Cushing, H. P., N. Y. State Mus. Bul. 115, p. 495. 2 Ogilvie, L. H., Jour. Geol., 10:397-412. 1902. 3 Fairchild, H. L., N. Y. State Mus. Bul. 160, pl. 11. 84 NEW YORK STATE MUSEUM giving birth to the South Meadows Lake. The uncovering of lower outlets to the west extinguished this lake which was succeeded by Upper Lake Newman. During this stage the ice lobe that lay in the East branch of the Ausable, eastern section, retreated to allow the Keene lake to form, with its drainage to the south. A further lower- ing of the waters caused a separation of the Boreas-Elk-Clear pond region from the major portion of the Keene lake, which continued to exist as a separate unit. A further subdivision brought about several smaller glacial lakes in the Schroon Lake quadrangle. The contin- ued withdrawal of the ice lobe uncovered the Wilmington notch and thus the Keene lake fell to the level of Upper Newman; bringing about a union of the two sections. Succeeding Upper Newman, Lower Newman held the stage until the withdrawal of the lobe in the Elizabethtown-Pleasant valley opened the side outlet channels in the center of the Ausable sheet, when the Saranac glacial waters held dominion, draining east. During the lower stages the western sec- tion was drained and only the eastern section was flooded. The Wilmington lake, drained through the Gulf; and the Upper Jay lake, both Upper and Lower phases, likewise drained to the east. The lakes that succeeded the Upper Jay lakes did not cover any portion of the Mount Marcy quadrangle and are not described in detail. The nature of the postlacustrine uptilting, which inclined the shore lines of the lakes northward, points to the conclusion that the land was experiencing uplift and warping while the ice was retreating from the region. The total amount of uplift since glacial times for the quadrangle may have been greater than 600 feet. eID EX Alling, Harold L., acknowledg- ments to, 6; Glacial geology, 62- 84; mentioned, 65, 71, 76 Anorthosites, 12, 23, 25, 28, 58; analysis, 31, 32; White face type, 33; inclusions in, 33-38; garnet reaction-rims, 38-46 Apatite, 26 Areal distribution of formations, 54-59 Augite, 25 Ausable chasm, 8- Ausable lakes, 8, 9 Ausable river, East branch, 7, 8; West branch, 7; contact on west bartk, 27 Avalanche lake, 8, 9, II, 34, 50, 58 Barite, 60 Basaltic dikes, 51, 58 Basic gabbro series, 58 Baxter mountain, 58 Boquet river, 8 Boreas ponds, 8, 10 Bostonite, 54 Brigham, A. P., cited, 57 Calcite, 20, 24, 60 Cascade lakes, 8, 9, 13, 17, 57 Cascadeyille, 17 Chapel pond, 9 Coccolite, 19 Colvin mountain, 7 Contact zones, 17 Contacts, near Owls Head, 20; south of Keene Center, 20; at the Weston mines, 22; on west bank of Ausable river, 27 Cushing, H. P., cited, 11, 12, 28, 33, 51, 54, 65, 75, 83 Dikes, 11, 20, 50; basaltic, 51, 58 Diopside, 20, 60; analysis, 19 Dix mountain, 7 Drainage, 8-9 | Fairchild, H. L., . Grenville series, Eakle, A. S., 54 Economic geology, 59-61 Edmond’s pond, 18 Edwards ponds, 9 Elk lake, 8, 10 Emmons, Ebenezer, cited, 17-18, 28 Erosional work, . 64-65 Escarpments, 7-8 cited, 64, 68, 73, 81, 83 Faults, 54-50 Fulton, Charles H,, acknowledg- ments to, 6 Gabbro-syenite, 50, 51, 58 Gabbro-syenite dikes, 11 Garnet-wollastonite rock, analyses, 21 Garnets, 13, 20, 24, 25, 26, 27,60; Gar- net reaction-rims in anorthosite, 38-46 Geological formations, statement, 10-28 Glacial drift, 11 Glacial geology, 62-84 Glacial terraces, 10 Gneisses, 12, 15-17 Gothics mountain, 7, 58 Granite, 50 Grenville gneiss, 36; inclusion in anorthosite, 35 general 10-28, 573) Stum-= mary, 27-28 Hedenbergite, 60 Hypersthene, 28, 30, 60 Johns brook, 36, 52, 54, 58 Johnson, D. W., cited, 64, 67 Keene Center, contacts south of, 20 Keene lake, 73 ; Kemp, dhe 19e cited, 33, 42, 43; 64, 68 ; comments, 47-48 [85] 86 NEW YORK STATE MUSEUM Labradorite, 61 Lake Newman, lower, 74 Lake Newman, upper, 71, 73 Lakes, 9-10 ‘Leeds, Albert B., cited, 20, 30, 53 Limestones, 12, 23 Long pond, 9, 17, 18 McComb mountain, 7 MacIntyre mountain, 7, 51 Magnetite, 13, 22, 24, 25, 26, 27, 50, 61 Marcy, mountain, 7; altitude, 5 Marsters, V. F., cited, 11 Miller, W. J., cited, 43, 65 Mineralogy, 59-61 Mount MacIntyre, 7, 51 Mount Marcy, 7; altitude, 5 Mud pond, 10 Newman, Lower lake, 74 Newman, Upper lake, 71, 73 Niagara brook, 7, 8 Niagara mountain, 7 Nippletop mountain, 7 North Elba, 7 Ogilvie, I. H., cited, 64, 65, 83 Opalescent river, 8, 30 Ophicalcite, 26 Ore Bed brook, 52 Orthoclase,. 61 Owls Head, contacts near, 20 Owls Head peak, 57 Pegmatite, 49 Physiography, 6-10 Pitchoff mountain, 7, 8, 13, 33, Porter mountain, 49 ts Potsdam sandstone, 27 Precambrian intrusives, 28-54 Quartz, 26 Rich, John L., cited, 67 — Ries, Heinrichs acknowledgments to, 6 Roaring brook, 35, 58 Roesler, Max, some garnet reaction- rims in anorthosite, 28, 39-46; mentioned, 6, 38 Rooster Comb mountain, 58 Ruedemann, R., cited, 65 St Huberts lake, 77 Saranac glacial waters, 75-77 Scott’s Cobble, 49, 50 Sericite, 21 Shanty brook, 9 South Meadows lake, 69-71 Syenites, 11, 23, 33, 49, 58 Table Top mountain, 7 Taylor, F. B., cited, 68 Trap dike, 50 Upper Jay lake, 80 Weston mines, contacts at, 22 Whiteface type of anorthosites, 33 Wilmington lake, 78-80 Wollastonite, 20, 61; analysis, 21 Zirkel, F., 43 ‘ PVENE NETS cseeeree Veer 8 Wray naa tatatat "9 Sar araTAraTA aT rotate 2 a AAT 4g . PP “evatarararatal EDUDATION DEPARTMENT JOHN M. CLARKE STATE GEOLOGIST UNIVERSITY OF THE STATE OF NEW YORK STATE MUSEUM BULLETIN aeteonk® 229-30 — Heney Gannett Chief Topographer H.M.Wilson. Geographer in charge. ‘ulation by U.S.Coast and Geoderle Survey. Topography by €.C.Barnard and J,H.Jennings. uPveyad in [B91-32sn cooperstion #ith the Grate of NewYork. 0% psc ‘awe 9nMT a a 1 Schroon Lake # MT. MARCY QUADRANGLE & Milew 9 Kilometers Contourinterval 20 feet, Draturre bee raedive wees level Geology by James F. Kemp Charles H. Fulton Harold L. Alling } Assistants LEGEND Pleistocene sands, gravels and moraine conceal the actual bed- rock which is conjec- tural. X\\ Post-Cambrian and Pre- cambrian basaltic dikes. 4/ Gabbro-Syenite dikes, ect IRA Syenite mixed with Grenville. Syenite with biue la- bradorite crystals from admixed anorthosite. Anorthosite Anorthosite Grenville Syntectic SF | Grenville limestone. Grenville schists and gneisses. 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